A super awesome rainbow heart is hidden inside of a chocolate bundt cake, what could be more fun? This easy Rainbow Heart Cake is made using boxed cake mixes, which just cuts down on the effort, without sacrificing the WOW factor.
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I first came across the idea for a hidden design cake while browsing online and instantly knew I wanted to make my own version. The surprise inside is what makes this cake so special and fun to serve.
Each slice reveals a colorful rainbow heart, adding a playful twist that's just as enjoyable to look at as it is to eat. It's a great way to turn a simple cake into something memorable.
This rainbow heart cake works beautifully for many occasions, from Pride celebrations to graduation BBQs or rainbow themed birthday parties.
With a straightforward design and a little extra effort, you can create a dessert that truly stands out. For more rainbow inspired recipes, check out Rainbow Grilled Cheese, Birthday Cake Overnight Oats, and Easy Rainbow Unicorn Cake.
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💛 Why You'll Love This Recipe
- Unique and fun. A bundt cake is great, but slicing into one with a colorful heart hidden inside makes it extra special and always gets a reaction.
- Easy to make. It may look impressive, but this cake is quicker and easier to assemble than it appears.
- Simple ingredients. Using boxed cake mix keeps things affordable and convenient. It's the same shortcut we use in recipes like Southern Banana Pudding Cake and Chocolate Pistachio Bundt Cake.
🛒 Ingredients
Yellow or white cake mix. This light colored cake forms the rainbow heart center and is easy to tint with food coloring.
Chocolate cake mix. Used for the outer cake layer to create contrast around the hidden heart.
Food coloring. Rainbow colors bring the heart design to life. Gel food coloring works best for vibrant color.
Chocolate ganache ingredients. Chocolate chips, and heavy cream or milk combine to create a smooth chocolate coating for the cake.
See the recipe card below for full ingredients and instructions.
💰 Budget-Friendly Tips
Buy food coloring once. A basic set of food coloring can be reused across many baking projects.
Keep ganache simple. Chocolate chips and cream make an easy, cost-effective frosting without specialty ingredients.
Save cake scraps. Extra cake pieces can be frozen and used for cake pops or trifles later.
🥄 Instructions for Rainbow Heart Cake
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 (Image 1).
Step 3: Whisk together until well mixed (Image 2).
Step 4: Divide the batter into 6 bags or bowls (Image 3).
Step 5: Add food coloring to each one and mix until the desired color (Image 4). 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 (Image 5).
Step 7: Bake at 350F for 10-15 minutes (Image 6). 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 (Images 7&8). 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 (Image 9).
Step 12: Whisk together until smooth (Image 10).
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 (Image 11).
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 (Image 12).
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 (Image 13).
Step 17: Bake in your oven at 350F degrees for 35-40 minutes until cooked through (Image 14). Let cool in the cake pan for 10 minutes before flipping over onto a wire rack and removing from the pan.
Step 18: Place onto a plate (Image 15). Frost with the chocolate ganache (recipe in card below) and add sprinkles (Image 16).
Step 19: Allow 10 minutes or more to set and cool completely.
Cut and serve your rainbow heart cake.
👩🏻🍳 Expert Tips
- Choose the right cutter. Use a heart shaped cookie cutter that fits comfortably inside the pan with a little extra space around it. A multi size set is helpful.
- Arrange colors thoughtfully. Place red and lighter colors on the outside with darker colors, like purple, toward the center for the best contrast when slicing.
- Freeze the hearts. Freezing the cut out hearts makes them easier to handle and helps prevent breaking during assembly.
- Stack carefully. Stack the frozen hearts in groups of 3-4 and avoid overcrowding so they bake evenly and stay centered.
❄️ Storage and Make Ahead
Storage: Store the finished Rainbow Heart Cake covered at room temperature for up to 3-5 days.
Make Ahead: The colored heart cake layer can be baked, cut, and frozen in advance. Assemble and bake the final cake when ready.
🥗 Side Dishes or Pairing Ideas
This rainbow heart cake pairs well with fresh fruit, ice cream, dessert tables, party spreads, or served as a centerpiece cake for birthdays and celebrations.
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❓ Rainbow Heart Cake 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.
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🐝 If you tried this Rainbow Heart Cake, please leave a ⭐️ star rating and share your buzz in the 💬 comments below. I'd truly appreciate it!
📖 Recipe
Rainbow Heart Cake
Ingredients
Rainbow Heart Cake
- 1 box (15.25 ounces) yellow cake mix, prepared according to package directions - ($1.80)
- Rainbow food coloring, as needed
Chocolate Cake
- 1 box (15.25 ounces) devil's food cake mix, prepared according to package directions - ($1.80)
- 1 tablespoon cocoa powder - ($0.09)
Chocolate Ganache
- 1 ⅓ cup semi-sweet chocolate chips - ($1.74)
- 1 cup heavy whipping cream - ($1.49)
Instructions
- Preheat & Prep: Preheat the oven to 350°F. Line a baking sheet with parchment paper.
- Prepare Yellow Cake: Prepare the yellow cake batter according to package directions.
- Color the Batter: Divide the batter evenly into 6 bowls or piping bags. Add food coloring to each portion and mix until the desired colors are achieved. Transfer to piping bags if needed and snip the corners.
- Pipe & Bake Hearts: Pipe thin stripes of colored batter onto the prepared baking sheet, keeping the stripes narrow so they fit within a heart shape. Bake for 10 to 15 minutes until set. Allow to cool for 10 minutes.
- Cut & Freeze Hearts: Cut heart shapes from the baked cake, placing them close together to maximize use. Discard scraps. Freeze the hearts for 10 to 30 minutes to firm.
- Prepare Chocolate Batter: Prepare the devil's food cake batter according to package directions.
- Prep the Pan: Grease a bundt pan thoroughly and dust with cocoa powder to prevent sticking.
- Add Base Batter: Pour about 1 cup of chocolate batter into the bottom of the pan, spreading it into a ring.
- Insert Hearts: Stack frozen hearts in groups of 3 or 4 and place them upright in the pan with the points facing up. Fit them snugly to minimize gaps.
- Fill & Bake: Pour the remaining chocolate batter into the pan, covering the hearts completely. Bake for 35 to 40 minutes, or until a toothpick inserted comes out clean.
- Cool: Let the cake cool in the pan for 10 minutes, then invert onto a wire rack to cool completely.
Make the Chocolate Ganache
- Heat the Cream: Place the chocolate chips in a heat safe bowl. Heat the heavy cream in the microwave for 1 to 1 ½ minutes until very hot but not boiling.
- Combine: Pour the hot cream over the chocolate chips. Cover and let sit for 5 minutes.
- Whisk: Remove the cover and whisk until smooth and glossy.
- Finish the Cake: Pour the ganache over the cooled cake. Allow it to set for at least 10 minutes before slicing and serving.
Notes
- Heart Cutter Size: Use a heart shaped cutter that fits comfortably inside the bundt pan with room to spare. Having multiple sizes can be helpful.
- Color Placement: For the most visible heart design, place lighter or red tones on the outer edges and darker colors like purple in the center.
- Freezing Tip: Freezing the cut hearts makes them easier to handle and helps prevent breakage during assembly.
- Stacking Hearts: Stack hearts in groups of 3 or 4. Too many at once can create straight lines, while too few may allow batter to seep between layers.
- Storage: Store the cake at room temperature for 3 to 5 days, similar to a standard boxed cake.
Nutritional Information
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