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M&M rainbow mosaic cake

Rainbow Mosaic Birthday Cake

Linda Appiah
This M&M rainbow mosaic birthday cake is a perfect cake for any rainbow lover.
Prep Time 20 mins
Cook Time 35 mins
Decorating Time 50 mins
Total Time 1 hr 45 mins
Course Dessert
Cuisine American
Servings 12
Calories 300 kcal


For the Vanilla Cake

  • cups cake flour
  • 1 tablespoon baking powder
  • 1 teaspoon salt
  • 1 cup (2 sticks) unsalted butter at room temperature
  • 2 cups granulated sugar
  • 4 large eggs
  • 2 teaspoons pure vanilla extract
  • 1 cup buttermilk at room temperature

For the Coconut Buttercream

  • cups (3 sticks) unsalted butter (soften)
  • cups powdered sugar
  • 4 tablespoons ( ¼ cup) coconut milk
  • 1 teaspoon coconut extract

For the Decoration

  • 1 bag (20 ounces) M&M candy


For the Cake

  • Preheat the oven to 350 °F or 180 °C. Prepare three 6 inches round cake pan with nonstick cooking spray or homemade pan release and set aside until ready to use.
  • In a medium bowl, sift the cake flour into it. Add baking powder, and salt to the flour and whisk together. Set aside.
  • In a large bowl with a hand mixer or a stand mixer fitted with the paddle attachment, cream the sugar and butter until light and fluffy about 3- 4 minutes. Scrape down the sides of the bowl and mix again for a minutes.
  • Add the eggs one at a time and mix well after each addition on a medium speed until smooth. Add the vanilla extract and mix well for 30 seconds.
  • Reduce the speed of the mixer and add a third of the dry ingredients, alternating with half of the buttermilk. Repeat with the dry ingredients and buttermilk until they are fully mixed. Add the last third of the dry ingredients and mix well. Stop the mixer and scrape the sides of the bowl and mix until smooth.
  • Divide the cake batter among the 3 prepared cake pan. Place the pans on the center rack of the oven and bake for about 30 -35 minutes or until a toothpick is inserted into the cake and comes out clean and dry. Bring the cake out of the oven and allow to cool in the baking pan for 10 minutes before transferring them to the cooling rack to cool completely

For the Coconut Buttercream

  • In a bowl of a stand mixer fitted with the paddle attachment or a medium bowl with a hand mixer, cream the butter on a medium-high speed until smooth. Slowly add the powdered sugar one cup at a time. Add the coconut milk and extract and beat until well mixed. Scrape down the sides of the bowl and mix the frosting on medium-high for about 3 minutes until light, fluffy and smooth.

Assembly the Cake

  • To assemble the cake, place a nonslip mat on a turntable and then tape a 6 inches cake cardboard circle to an 8 inches cardboard circle and place the cake board on the turntable.
  • Apply a small amount of buttercream to the center of the 6 inches cake board. Place the first cake on the board, add buttercream, and spread it evenly on the cake and place the second cake layer on top of the frosting and repeat the process until all the cakes are stacked.
  • The last cake layer should be placed flat side up that is the bottom should face up. Press down on the stacked cakes lightly to help the cakes stick to the icing. Crumb coat the cake with a thin layer of buttercream and smooth it with a cake scraper. Refrigerate the cake for about 30 minutes or 10 minutes in the freezer. Add the final thick layer of buttercream frosting and smooth it.
  • Place the candy onto the cake using the pattern created as a guide. Start from the bottom of the cake and work your way up. Make sure there is no space between the cake and cake board when placing the candy on the cake. When you get to the top of the cake, fill in as shown in the cake design.
  • Place the cake in the fridge to set the decorations. Take a photo, serve, and enjoy!


Calories: 300kcal
Keyword Birthday Cakes, Cakes, Mosaic, Rainbow
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