A super awesome rainbow heart hidden inside of a chocolate bundt cake, what could be more fun? This Rainbow Heart Cake is made using boxed cake mixes, which just cuts down on the effort, without sacrificing the WOW factor.
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!
Notes
Choose a heart-shaped cookie cutter that fits inside the pan with some room to spare. An assorted size pack can be helpful to ensure you have the right sizes.To make the heart design more visible when sliced, arrange the red and lighter colors on the outer sides of the heart shape, with purple in the middle. This will create a contrasting effect.Freezing the cut hearts before use makes them easier to handle and prevents breakage.When stacking the hearts, use 3 or 4 layers at a time. Too many at once may result in straight lines and an uneven heart circle, while too few will increase the chances of chocolate batter seeping between the hearts.The cake will stay fresh for about 3-5 days at room temperature, similar to a normal boxed cake mix.