Rainbow Heart Cake

“I don’t worry
Whenever skies are gray above 
Got a pocketful of rainbows
Got a heart full of love

-Elvis Presley, “Pocketful of Rainbows”

I made a cake the other day. It’s a colorful cake. It’s colorful on the outside, and it’s colorful on the inside. You’ll see.

Have you guys ever visited Amanda over at i am baker?? If you haven’t, why. not?! You are missing out. Big time. On this, this, all of these, this, these, and this. Amazing, huh? Plus, Amanda is incredibly talented, but she’s also a very kind and generous person. She does wonderful things for others, for no other reason than to be helpful and good. She inspires me so much. You seriously need to check her out, if you haven’t already.

Back in December of last year, for my very last post of the year, I wrote a list of kitchen resolutions for 2011. My number one resolution was to make Amanda’s amazing heart cake. Amanda has a lot of incredible “surprise” cakes on her blog, like this one and this one. They’re fantastic, and I’ve always been enthralled with them. The best part is that she shares tutorials on how to make them! But the heart has always been my very favorite.

When I finally got up the nerve to give it a try, I knew I wanted to try to do something new to it…something to make it my own. I’ve always wanted to make a beautiful rainbow layer cake too, but I’ve seen soooooooooo many on the Internets lately, how on earth can I find a new way to present it that hasn’t already been done a bazillion times?!

That’s when a crazy stupid idea hit me, and I decided to combine Amanda’s heart cake with a rainbow layer cake. Alright, I say crazy and stupid….well, it was, but it was also crazy fun.

And, if I might just pat myself on the back for a half second, it’s crazy pretty too. 🙂 It’s nowhere near as gorgeous and absolutely perfectly proportioned as Amanda’s creations, but I’m pretty darn pleased with it. It still needs some work, some practice, but I think that I might just have it down in one or two more cakes. I would have liked for my heart to be more rounded in all the places it’s supposed to be round, but I couldn’t do a whole lot of carving away, since I was using the cakes I was cutting away as the rainbow layers.

See, I made two rainbow layer cakes. Okay. I started with two 6-inch, six-layer cakes. Wait. Well. I baked two recipes for an eight-inch two-layer cake, but I baked them as 6-inch rounds instead, and ended up with six total (six six-inch round cake layers, one red, one orange, one yellow, one green, one blue, and one purple). Each layer was sliced in half, creating a total of 12 layers (two of each color). Which gave me two six-inch, six-layer cakes, but they were stacked in opposites… Am I losing you? Here…let me show you.

K. My cakes are baked…

So first off, I made the filling frostings. Each one was just a couple of tablespoons of my main frosting with food coloring (Wilton gel colors, which I also used in the cake batter, as well as the fondant) added. Since I’d only need five layers of filling frosting, I skipped the red. Red or purple are the two color options that can be skipped, since those are the top/bottom layers. I went with red because I can make purple with less food coloring. What can I say? I’m cheap and lazy! 😉 If you’re even cheaper and lazier (which I fully intend to be next time) skip the colors altogether and just use white frosting!

Anyhoo. After slicing each layer in half, I frosted the tops of the cakes with corresponding filling colors and stacked them into two stacks of three layers each (red, orange, and yellow in one stack, and green, blue, and purple in the other stack). Repeat this process with your second cake.

When all was said and done, I had two stacks of red, orange, and yellow cake, and two stacks of green, blue, and purple cake. Now, you’ll notice in this photo that the green, blue, and purple layers on the left are on a cake board. They are the bottom half of one cake (with the cakes behind them making up the top half). Conversely, the red, orange, and yellow cakes on the right are on their own cake board and will be the bottom half of the second cake (with the cakes behind them creating the top half).

Once the cakes are trimmed, hollowed, refilled, and stacked, you end up with two pretty rainbow layer cakes going in opposite directions.

But first you have to trim, hollow, refill, and stack them. I began following Amanda’s instructions very closely, except that I needed to keep extra carving to a minimum, since my goal was to use the layers that I removed from cake one to created the heart inside cake two (Amanda fills hers with red velvet cake crumbs…totally makes more sense…what was I thinking?). Amanda instructs that you should create a guide to make sure that your layers will line up (brilliant).

Next, you cut the bottom of the heart out by slicing along the guide you created and into the cake, making a cone shape. Try to be as neat and even here as you can, and be sure to get your knife point centered (and keep it there) while you slice, or you may end up with a flat-bottomed heart. Which is still totally cute, both of mine ended up slightly flat bottomed in sections.

Now the top part is where things got tricky. So tricky that I forgot all about my darn camera and have nothing to show for you. My best advice is to hit up Amanda’s tutorial again, but as I said before, if you do your cake my way, you really need to keep the carving to a minimum. I tried to use a spoon to cut the top half of the cake out, and it worked. Sort of. I got a curve to the top half that I wouldn’t have gotten with a knife, and was able to eliminate a lot of carving, but I still didn’t get a great shape, and it was very messy since the spoon wasn’t cutting so much as ripping. Once the cakes were assembled and sliced open (after sitting for several hours), gravity had done a good job of filling in my goofs, but I am going to try this again and again, until I get it right, then I’m going to write a massive, super detailed tutorial. Hopefully, it won’t take a billion tries.

Once the cakes were fully carved, I placed the filler layers into the opposite colored cakes (that’s just the bottoms pictured, the tops are still whole and uncut).

Next, (after carving up the top halves of the cakes) I put a little filling frosting on one half (green works for both sides), and slapped them together. Really. I slapped them. Together.

I chilled the cakes for a half hour or so, then gave them a quick crumb coat before chilling them again (another half hour). Once chilled, I covered the cakes in a generous finishing coat of smooth, pure white frosting. Then I moved on to the decorations. 🙂

At this point, I had absolutely no idea how the insides were going to look, so I decided that the outsides needed to be fun and beautiful. So that I’d still have cute cakes to show you guys. Because I was sure the inside would be an utter failure.

So I made pretty fondant colors…


…and lots…

…and lots of pretty fondant colors. I made at least two shades of each of the cake layer colors to use on the outside of the cake (I used the same food coloring for each shade, just adding more or less, as needed, to achieve the shade I wanted). Then I busted out my little flower cutters (from Wilton Gum Paste Flowers Set) and made about a trillion tiny flowers and dots. It was a lot of bits, but super fast since I used little cutters.

I loved all of the bursts of color, and the variety of shapes so much that I decided to keep it minimalistic in detail. I think it balances out the busy-ness of the decorations. Keeping them clean and simple makes their shapes and colors that much more interesting and beautiful. This is such a happy cake. Even if the inside were plain, or just a lovely rainbow layer cake, it’s gorgeous. And happy. And makes me smile. 🙂

Fortunately, when I sliced into the cake, I actually saw a halfway decent heart. Thrilled doesn’t even begin to cover how excited I was.

I know that with just a couple more takes, I’ll have a heart that can be proud to say it was inspired by i am baker. In the meantime, I’m gonna go have some cake. 🙂

Thank you, Amanda, for the inspiration and perfectly clear tutorial!

Recipes used for this cake:

2 recipes Yellow Cake

1 1/2 recipes Vanilla Buttercream

Marshmallow Fondant

All linked recipes by Darla

Leave a comment


  1. giselle lama says

    que bonita! y col colores intensos que colorantes son y una pregunta cuando la comes el colorante mancha muco la boca pues los que yo uso cuando son colores intensos manchan la boca un monton gracias!un saludo!

  2. says

    O. M. G.

    You blew my mind before you cut into the cake. Then when you showed the cutaway with the heart, my brain literally fell out of my head and on to the floor. It still hasn’t gotten up.

    You are so creative and talented. Amazing!!!

  3. says

    This cake is amazing! I can’t believe you made this…I would never guess that someone could make a cake so colorful on the inside like that! You’re very talented! Would you mind it if I shared it on my blog? I would put all of your info! I could feature it under my heavenly cakes!!! 🙂

  4. Kim C. says

    OH MY GOSH!!!! That is an ABSOLUTELY BEAUTIFUL cake!!!! I’ve never seen any kind of cake design like that anywhere and I think its INCREDIBLE and definitely ORIGINAL. The colors are so vibrant and cheery and I LOVE IT! 😀

    • says

      Hi Norma, Thank you. 🙂 The best advice I can give for coloring fondant is to be patients, be prepared to make a mess, and use gel colors.

      I make my fondant colors by starting with a little bit of the color that I want to use, kneading it into the fondant thoroughly, then adding a little bit more and a little bit more, until I get the color I’m hoping for. By starting out with just a little, I know I’ll end up with a color I’m happy with eventually. You can always add more color, but you can’t take it away once you’ve added too much.

      I’m always fully prepared to make a huge mess when I’m coloring fondant. Sometimes, with colors like black and red, you have to add so much color to get them right that you end up with an awful lot on your hands and work surface too. But don’t worry, it washed right off of the work area, and usually it’ll wash right off of skin too. Sometimes you may have bright pink fingers for a few days, thoguh. 🙂

      I always use gel color when I make fondant because you need less of it to make brighter colors than you do most liquid colors. I usually use Wilton gel colors becuase they’re widely available at Michaels and other craft stores, but I also really love Americolors, especially for red and black.

      I hope this is all helpful! 🙂

  5. Linda says

    I am speachless! This is so beautiful, my mouth fell open when I saw it. The heart in the inside, it just looked like so spent hours and hours baking the cake. I don’t even know what to say….

  6. says

    What a MASTERPIECE! So much time and patience and love….i’m in AWE!
    I’m glad i was sitting down when i saw this (via Foodgawker) or it would have blown me over!
    Well done! =)

  7. Karina says

    This is AMAZING, I’ve always wanted to make one of Amanda’s cakes too but never had the courage. It looks absolutely fantastic!

  8. Bttrflybabydoll says

    I knew you would knock this cake out of the park! Absolutely amazing! I will never be as good as you are, but man do I love to watch why you can do! Great job Darla!

  9. says

    This has got to be one of the most adorable cakes I have ever seen! I’m going to have to attempt this someday, since you’ve now given me the inspiration to tackle the challenge 🙂 Absolutely beautiful and it looks sooooo tasty!

  10. says

    That is unbelievable!! You definitely made it your own. How you even began to wrap your mind around the steps of how to accomplish that….I’m in awe!

  11. says

    I’m speechless. Really and truly, my mouth was hanging open as I looked at your pictures. This. IS. AMAZING. I pinned it, and expect it will be repinned from now until eternity! You are a cake goddess!

  12. Rebecca S says

    This cake is amazing! I want to make it! I think it would be awesome for a gender reveal party too! I want a video of how you cut it though I am so confused.

  13. Adelina says

    Lovely! I have to admire you for taking the time to do this. I think if I try, I would cry because I don’t have the patient nor the skill to perform this! But….the finished cake is truly beautiful!

    Thanks for sharing!

  14. says

    Hey i made this for my friends birthday and it was such a hit! it didnt turn out nearly as proprtioned as yours and some of my layers were bigger than others but overall a success, thanks so much!

  15. Alicia says

    I’m looking forward to make this cake on my birthday (just… without the hearth- it’s too much work for me haha) , and I want to know how many people came to your party – 20 people are coming to my house and I’m wondering if I do 1 or 2 recipes.
    Your cakes are adorable!

  16. Anne the Sconess says

    That is absolutely beautiful! The cake is somewhere between stunningly elegant and OMG super cute and cheery and whimsically romantic. It would definitely “Show the Love”. ;oD Thanks so much for sharing. I’m your newest fan!

  17. A.J. says

    Hi Darla, i just discovered this website and i’m loving it! And for a close friend of mine’s birthday i actually decided to do her a rainbow cake (not sure about the heart yet though) and want to use your cake and buttercream recipes but i was wondering if i can add cocoa powder and make the cream a chocolate one. Or do you think it’ll ruin the recipe? I checked the website a while but couldn’t find a chocolate frosting recipe except for a chocolate filling but i need something to cover the whole cake as well so i was wondering your opinion on this. Thanks for the help 🙂

  18. Tracey Mc says

    Wow! I really adore this cake. I’ve already decided I’m making a rainbow cake for my daughter this year, wonder if I should try this heart idea? Think my family will be sick of rainbow cake by then since I best practice (a lot)

  19. Mimi Teh says

    Love your site! I do have a question though…how can I manage MMF in hot and humid weather? I have gone through few sites/links on it but I am still timid to start. Any suggestion/s?

    • says

      In all honesty, I have found that the only way to truly manage fondant in humid weather is to have an air conditioned work area. When I lived in an extremely humid area, I stopped using fondant, except for smaller details, because no matter what I did, it always melted. I recommend having plenty of confectioners’ sugar or corn starch on hand to prevent sticking, and do NOT refrigerate it, or it will condensate and completely melt once it’s removed. I’m sorry I can’t be more helpful.

  20. Rebecca says

    I love this cake and can’t wait to make it for my daughther!! Do you have a recipe for the fondant? I’ve never worked with it have any advice?

    • says

      Hi Rebecca, you can find a link for the fondant recipe at the end of the post. 🙂 The best advice I can give is to take your time and be patient. And have plenty of confectioners’ sugar on hand. 🙂

  21. Molly says

    Hi! My friend and I are going to try to make this cake this weekend, but we have a few questions/concerns. Do you have any tips on making the top part of the heart? We’re worried that carving with a spoon will destroy the shape. How do you ensure that doesn’t happen?

    Also, do you have any tips for what to do with all that extra cake?


    • says

      Ho Molly, I answered some of your questions with the comment below, but as for the extra cake, I made two separate cakes. I actually froze one for about a week or so, then thawed it, frosted/decorated it, and served it later. I hope this is helpful. 🙂

  22. says

    My colleague and I are excited to try making this cake over the weekend, but we’re still a little shaky on making the top half of the heart. Do you have any tips for carving so you get the nice indentation at the top? And did you carve the filling of the heart, or did you just kind of make a v and then it settled into the right shape because the negative space was carved correctly?

    Thank you! This looks really spectacular.

    • says

      Hi Tamar, Just take your time and be patient. If you lose a bit of the heart shape. then you can press cake crumbs into place to help fill any gaps. Once the cake is assemble and frosted, you can’t tell if you used crumbs to fill a hole or not, even after cutting the cake, so it works great. When I carved my hearts out, I was pretty lucky to get everything pretty closely matched, but yes, the cake will settle into empty spaces, as long as they aren’t overly large. I hope this is helpful!

  23. Carla says

    Hi !

    I’m French, so my English isn’t perfect… Sorry !

    I love this recipe, the final is just BEAUTIFUL ! I made a Rainbow Cake 1 month ago and I wanted an other recipe, a best recipe… And I found it ! Thank you very much for your help in my search !
    I haven’t make the Rainbow Heart Cake yet, but I really want !

    Sorry for the misspellings again !

  24. Kristyn says

    Hi Darla,
    Looks fantastic, you are so creative!
    Just double checking, this was buttercream icing then fondant decorations?
    Did you find they bleed colour at all onto the white?
    Also any tips on sticking the fondant to the butter cream?
    Thanks alot 🙂
    (sorry for all the amateur questions!!)

  25. Maya says

    Oh my god! You are legend! The cake is absolutely beautiful just looking at it from outide, the colored layers made it superb but the reverse heart leaves me totally speachless! Absolute legend!

  26. Maddie says

    I love this cake and cant wait to try and make it
    I was thinking about how you could create the top ‘bumps’ of the heart and i was thinking maybe you could do the same as the bottom but make smaller cones slightly of center. This may take some time and maths calculations but I think it would work. So I am going to give this a try for a special friends 18th birthday and i wil comment on how it goes 🙂 won’t be until the end of november though

    Love the blog 🙂

  27. Billie says

    I have seen so many variations of rainbow cakes and “surprise inside” cakes and I have to say, yours is one of the most beautiful cakes I have ever seen. The outside decoration is really stunning and so fitting for what lies inside! I am truly inspired! Thank you for sharing this cake with us all!

  28. says

    Hi! This is the most amazing rainbow cake ever!! It’s a great inspiration, but I’m scared of trying… for sure is not going to be so perfect 🙂 Thanks for sharing!

  29. says

    i think it coooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooool

  30. Estelle Smith says

    I really would love to make this for my birthday in July, but i don’t have any cutters. Can you tell me where to buy the ones you used?

  31. Eleanor says

    Thanks a million for your designs and recipes, Darla! My 8 year old niece was thrilled with her rainbow cake (I didn’t do the heart…not quite ready to take that on). I used your yellow cake and buttercream frosting recipes. Delicious and beautiful – the cake was a real hit! I levelled the cakes off and used the remnants to make multi coloured cake pops.
    Love your site.