A super awesome rainbow heart hidden inside of a chocolate bundt cake, what could be more fun? This easy rainbow cake is made using boxed cake mixes, which just cuts down on the effort, without sacrificing the WOW factor.
I don't recall what I was originally searching for online one day but I came across the BBC Good Food's Recipe for a Hidden Heart Cake and inspiration hit. I instantly thought to myself that I needed to try it. But, the more I thought about it, the more inspired I became to make my own hidden design cake.
Nobody expects a surprise image inside their cake, which is what makes this recipe so much fun. It looks great, tastes delicious, and is packed with colorful fun in every slice.
It'd be the perfect cake for celebrating Pride month or taking to a graduation BBQ. It's also perfect for a rainbow-loving kid's birthday party.
With one simple design and a little effort, you can turn a simple dessert into one that people talk about for ages.
For more rainbow recipes, be sure to check out my Rainbow Grilled Cheese Sandwiches, and Pastel Rainbow Unicorn Cake.
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🍯 Why This Recipe Works
- It's unique. A bundt cake is fine and dandy, but slicing in to reveal a colorful center is always fun, especially when it's shaped like a heart. You'll definitely feel the love!
- It's easy to make. This recipe may look like it requires a lot of effort and time, but you'd be surprised to hear it's actually pretty quick and easy to assemble.
- Simple ingredients. We don't need much to make this recipe because we "cheat" and use boxed cake mixes as the base. This means it's affordable, convenient, and perfect for a sweet treat.
🥘 Ingredients
Ingredient Notes:
Yellow Cake Mix- You will need a box of yellow cake mix or white cake mix. This is what will be the center of the bundt.
Chocolate Cake Mix- For a rich chocolate outer exterior, use Devil Food Cake chocolate cake mix or plain chocolate cake mix.
Food Coloring- Use some rainbow colored food coloring to create the center heart. I prefer gel food coloring because it's more vibrant.
Cocoa Powder- You'll want some additional chocolate in the form of cocoa powder. This really helps to make our dessert more indulgent.
Chocolate Chips- You can use semi-sweet chocolate chips or milk chocolate chips, depending on what you'd prefer.
Heavy Cream or milk- This will make the chocolate into a more ganache-like frosting to coat the cake with.
For specific ingredients and measurements, please see the recipe card below.
🔪 Instructions
Step 1: Preheat your oven to 350F degrees and line a baking sheet with parchment paper.
Step 2: Add yellow cake mix, eggs, oil, and water to a large mixing bowl.
Step 3: Whisk together until well mixed.
Step 4: Divide the batter into 6 bags or bowls.
Step 5: Add food coloring to each one and mix until the desired color. Place into baggies and snip a corner of each bag.
Step 6: Slowly pipe stripes of color on the baking sheet until it's filled in. Make sure to keep the stripes thinner so you can fit them all in a heart.
Step 7: Bake at 350F for 10-15 minutes. The time will vary based on the thickness of your batter in the pan.
Step 8: Let cool for 10 minutes before cutting into hearts (they're less likely to break this way).
Step 9: Cut hearts in the cake, close together to squeeze in as many as possible. Remove the scrap cake pieces as those are not needed.
Step 10: Freeze the hearts for 10-30 minutes.
Step 11: Place the chocolate cake mix, eggs, oil, and water in a mixing bowl.
Step 12: Whisk together until smooth.
Step 13: Grease the inside of your bundt pan and dust it with 1 tablespoon of cocoa powder to keep the cake from sticking.
Step 14: Pour in about 1 cup of cake batter (a little more won't hurt). Try to get the batter to make a ring around the pan.
Step 15: Stack your frozen hearts in 3 or 4 at a time and place them in the pan. Try to avoid as many cracks as you can. Place the bottom points facing up.
Step 16: Fill in the bundt pan with the remaining chocolate cake batter, and make sure to cover the ends of the hearts that are sticking up.
Step 17: Bake in your oven at 350F degrees for 35-40 minutes until cooked through. Let cool in the cake pan for 10 minutes before flipping over onto a wire rack and removing from the pan.
Step 18: Frost with the chocolate ganache (recipe in card below) and add sprinkles.
Step 19: Allow 10 minutes or more to set and cool completely.
Cut and serve your cake.
🍴 Recipe Tips
You want the cookie cutter to fit inside of the pan with room to spare. I didn't know what size heart cookie cutters I needed so I bought an assorted size pack to make sure my bases were covered.
If you want the heart to pop more when sliced into, try and get the red and lighter colors of the rainbow on the outer sides of the heart with purple strip down the middle. This will help it to look less hidden once sliced. In person, it's much more vivid than in photos.
Freezing the hearts after cutting them makes them easier to handle and place. I do not recommend skipping this step as the hearts can break and make life a bit difficult.
Stack your hearts in 3 or 4 of height at a time and place them in, too many at once will cause straight lines and uneven heart circle whereas too few will allow more chances for the chocolate batter to get between the hearts.
💭 FAQs
If you slice this cake and find a little chocolate covering the heart and ruining the perfect image you had in mind I have a great tip. Simply shave off a small piece of cake. A very thin layer right off of the side of that one you just cut is all you should need.
This cake lasts as long as a normal boxed cake mix should. About 3-5 days at room temperature before getting dry and sad.
Nope! I had None of my stripes matched up to the piece in front of it. You can't even tell! The pieces all fuse together when baked so as you slice it comes out looking awesome. It is a little more noticeable when you do vertical and horizontal stripes side by side but it looks like tie-dye spots, not lines.
❤️ More Delicious Cake Recipes
If you tried this Hidden Rainbow Heart Bundt Cake, please leave a ⭐️ star rating and share your feedback in the 📝 comments section below. I would truly appreciate it!
📖 Recipe
Hidden Rainbow Heart Bundt Cake
Ingredients
- 1 box (15.25oz) Yellow Cake Mix, Prepared ($1.72)
- 1 box (15.25oz) Devils Food Cake Mix, Prepared ($1.72)
- Rainbow Colored Food Coloring ($0.04)
- 1 Tablespoon Cocoa Powder ($0.10)
Chocolate Ganache
- 1 ⅓ cup Semi-Sweet Chocolate Chips ($1.10)
- 1 cup Heavy Cream ($0.74)
Instructions
- Preheat your oven to 350F degrees and line a baking sheet with parchment paper.
- Add yellow cake mix, eggs, oil, and water to a large mixing bowl. Whisk together until well mixed.
- Divide the batter into 6 bags or bowls. Add food coloring to each one and mix until the desired color. Place into baggies and snip a corner of each bag.
- Slowly pipe stripes of color on the baking sheet until it's filled in. Make sure to keep the stripes thinner so you can fit them all in a heart.
- Bake at 350F for 10-15 minutes. The time will vary based on the thickness of your batter in the pan. Let cool for 10 minutes before cutting into hearts (they're less likely to break this way).
- Cut hearts in the cake, close together to squeeze in as many as possible. Remove the scrap cake pieces as those are not needed. Freeze the hearts for 10-30 minutes.
- Place the chocolate cake mix, eggs, oil, and water in a mixing bowl. Whisk together until smooth.
- Grease the inside of your bundt pan and dust it with 1 tablespoon of cocoa powder to keep the cake from sticking.
- Pour in about 1 cup of cake batter (a little more won't hurt). Try to get the batter to make a ring around the pan.
- Stack your frozen hearts in 3 or 4 at a time and place them in the pan. Try to avoid as many cracks as you can. Place the bottom points facing up.
- Fill in the bundt pan with the remaining chocolate cake batter, and make sure to cover the ends of the hearts that are sticking up.
- Bake in your oven at 350F degrees for 35-40 minutes until cooked through. Let cool in the cake pan for 10 minutes before flipping over onto a wire rack and removing from the pan.
- Frost with the chocolate ganache and add sprinkles. Allow 10 minutes or more to set and cool completely.
- Cut and serve your cake.
How to make the chocolate ganache
- Add your chocolate chips to a mixing bowl and add your heavy cream to another.
- Microwave the heavy cream for about 1 minute to 1 minute and 30 seconds. It should be scalding hot but not boiling.
- Pour the heavy cream over the chocolate chips and immediately cover the bowl and let it rest for 5 minutes undisturbed.
- Remove the cover and whisk until smooth and velvety.
- Pour the ganache over the cake.
- Allow 10 minutes or more to set and cool completely.
- Cut and serve your cake. Enjoy!
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