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4.72 from 21 votes
Rainbow Cake, Gemma Stafford, Recipe
How to Make a Double Rainbow Cake
Prep Time
30 mins
Total Time
30 mins
 

Learn how to make a Double Rainbow Cake at home with a beautiful Ombre Rainbow effect and lovely Vanilla Buttercream frosting!

Course: Dessert
Cuisine: American
Servings: 8
Author: Gemma Stafford
Ingredients
  • 3 2/3 Cups (25ozs/710g) Cups all-purpose flour (or cake flour)
  • 1 tsp baking powder
  • 1/2 tsp baking soda
  • 1 tsp salt
  • 1 1/2 Cup (12oz/ 340g) granulated sugar
  • 1/2 Cup (4oz/115g) light brown sugar
  • 1 Cup (8oz/ 225g) butter, melted
  • 2 Large egg
  • 1/2 Cup (4oz/113g) yogurt plain or sour cream
  • 1 1/2 Cup (12oz/340g) Buttermilk (make buttermilk by mixing milk with 3 tablespoons of lemon juice or white vinegar)
  • 2 Tbsp vanilla extract
  • Food dye (Good quality and concentrated) red, yellow, orange, violet, blue and green
  • VANILLA BUTTERCREAM FROSTING
  • 1 1/2 cups (12oz/340g) Butter, at room temperature
  • 3 cups (1lb 8oz/ 6bog) Icing sugar, sifted
  • 2 tsp Vanilla extract
Instructions
  1. Preheat oven to 350F degrees. Grease and line a 9 inch springform or baking pan. I used a 6inch to get a higher cake. If you do you will have some mix left over for cupcakes.
  2. In a medium bowl mix together all the dry ingredients, flour, baking powder, baking soda, both sugars and salt.
  3. In a bowl, melt butter in the microwave and set aside.
  4. In a jug , whisk in the wet ingredients minus the butter- egg, yogurt, buttermilk, and vanilla extract until combined.
  5. Slowly mix the wet ingredients into the dry. Towards the end of mixing add in the melted butter. The batter will be thick. Do not beat or over mix as this will toughen your cake.
  6. To color the cake: Divide the batter into 6 bowls. Add a generous drop of food dye to each bowl. Mix until you have reached your desired color. Try to add enough at the start to avoid over mixing your cake batter.
  7. Now for the fun part: Spoon the batter into prepared cake pan, alternating the color. Lay the colors over each other to create a beautiful marbled effect in the end cake.
  8. IMPORTANT NOTE: Bake for roughly 45-55 minutes. Depending on size cake you make 1hr 10- 1hr 20 minutes or until a toothpick inserted in the center comes out clean. This is a thick cake so it will take some time.
  9. To make the Buttercream- On Medium speed beat the butter for about 8-10 minutes on its own. This makes a huge difference in the end so be patient and you will be rewarded with amazing frosting.
  10. When pale in color, add powdered sugar spoonful by spoonful on Low speed. This helps make a fluffy frosting too.
  11. Turn off the mix and run a spatula under and around the frosting to make sure all ingredients are incorporated. Add vanilla and salt and beat on medium speed for another 5 minutes. The frosting will almost double in size and will be so fluffy and pale in color. It helps to chill your frosting before use so its not too soft.
  12. Color your frosting with drops of food dye like you did with the cake batter until you reach your desired color.
  13. Slice your cake in layers. I did 5 layers, but you can do as many or as little as you like.
  14. Spread your colored frosting in the layers of the cake to continue the rainbow color. Then spread the overflowing icing around the cake to create the crumb layer. Pop in the fridge for 20 minutes and let the icing set. This will make it easier to do the final coating.
  15. To create an Ombre Rainbow on the outside - With a small spatula (or even a knife) spread thin line of your frosting around the bottom and work up your way up the cake going from dark to light. I did purple, blue, green, yellow, orange and red on the top. It will be rough, and there will be bumps and holes but don’t worry :).
  16. Once you have done a thin line of all of your colors take a spatula and run it GENTLY around the cake blending and smoothing the colors. You don’t want to take away frosting doing this, just smooth the end result. Now enjoy your amazing Double Rainbow Cake creation!

Watch the Recipe Video!