Chocolate Rainbow Cake “Moonbow Cake” Recipe

Rich chocolate bundt cake with a dense, tight crumb and a beautiful rainbow surprise inside!  

Chocolate Rainbow Cake – 226 g unsalted butter – 75 g refined coconut oil melted or solid – 400 g granulated sugar – 1 tsp fine sea salt – 2 tsps baking powder – 2 teaspoon pure vanilla extract – 4 large egg whites plus 1 egg yolk – 360 g cake flour – 250 g plain kefir or buttermilk plus another 20g – 40 g dutch process or black cocoa Chocolate Glaze – 1 cup powdered sugar 130g – ¼ cup dutch process cocoa – ¼ cup milk more as needed – Pinch fine sea salt – 1 tsp pure vanilla extract




Preheat oven to 350 F. Butter and flour large bundt pans. Cream butter, coconut oil, sugar, salt, vanillas, and baking powder for 5 minutes until fluffy.  

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STEP  1 .

Each egg white should be added to the mixer and mixed until fully incorporated. Slowly add buttermilk to the sifted flour mixture. Put 1/3 cup batter in 5 bowls. 

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Add red, yellow, green, blue, and purple gel food coloring to bowls. Add cocoa, egg yolk, and buttermilk to remaining batter. Mix well.  

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Fill your bundt pan mostly with cocoa batter. Finish with the rainbow-covered top. Cut the tops of five colored batter piping bags. A teaspoon makes a chocolate batter moat.  

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To widen the moat, pipe a red circle into it and smooth it with a spoon, leaving a white border on the inner and outer rim. Keep both sides red and add yellow.  

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The photos above show each color narrowing. To avoid smooshing the rainbow, spoon the remaining chocolate batter on top with an offset spatula. 

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Bake 45 minutes after checking doneness at 40. Finished bundt springs back when touched. Invert cake onto cooling rack after 15 minutes in pan.  

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See Also

Lemon Curd Cheesecake recipe