Ingredients

• Cake
  • 2 3/4 cups cake flour
  • 1 tsp baking powder
  • 1 tsp baking soda
  • 1 tsp salt
  • 1 cup unsalted butter, softened to room temperature
  • 1 cup granulated sugar
  • 1/3 cup macadamia nut oil (secret ingredient)
  • 3 large eggs, at room temperature
  • 2 large egg whites, at room temperature
  • 2 teaspoons pure vanilla extract
  • 1 cups buttermilk, at room temperature
  • 3/4 cup rainbow chips (dye free ones can be found online)
• Vanilla Buttercream
  • 1 cup unsalted butter, softened to room temperature
  • 2 cups confectioners’ sugar
  • 1/8 cup heavy cream, at room temperature
  • 2 tsp pure vanilla extract (or use clear imitation vanilla extract for stark white frosting)
  • 1/8 tsp salt
  • optional: additional chips for garnish

Instructions

• Preheat oven to 350°F
• Spray two 8-inch or 9-inch cake pans, line with parchment paper rounds, then grease the parchment paper 
• Whisk the cake flour, baking powder, baking soda, and salt together in a large bowl. Set aside
• Using a handheld or stand mixer fitted with a paddle attachment, beat the butter and sugar together on high speed for five full minutes, until they are completely combined and fluffy. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. Add the oil and beat for 1 minute until combined. Add the eggs, egg whites, and vanilla extract and beat on medium-high speed until combined. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed
• Add dry ingredients and buttermilk in three additions, mixing after each addition just until incorporated. Do not over-mix this batter. The batter will be velvety and thick. Gently fold in the chips. Pour and spread the batter evenly into each cake pan
• Bake for approximately 25–26 minutes, or until the cakes are fully cooked through. (8-inch cakes may take about 27–28 minutes.) Tent the cakes with foil after about 15 minutes to prevent the sides and top from over-browning
• Allow the cakes to cool in the pans for 20 minutes, then set them on a wire rack. Run a knife around the edges and then remove cakes from pans. Place cakes directly on wire racks to cool completely. The cakes must be completely cool before frosting and assembling.
• In a large bowl using a handheld mixer or stand mixer fitted with a whisk or paddle attachment, beat the butter on medium speed until creamy, about 2 minutes. Add confectioners’ sugar, cream, vanilla extract, and salt. Beat on low speed for 30 seconds and then switch to high speed and beat for 2 minutes. Add more confectioners’ sugar if the frosting seems too thin; more cream if the frosting is too thick; or an extra pinch of salt if the frosting is too sweet
• Place one cake layer on your cake stand, cake turntable, or serving plate. Using a flat icing spatula or a small offset spatula, evenly cover the top with approximately 1 cup (250g) of frosting. Repeat with the second cake layer, and one more cup of frosting
• Spread the remaining frosting all over the top and sides. Garnish with extra chips, if desired