Ingredients:

  • 420g cake flour
  • 400g granulated sugar
  • 1.5 tbsp baking powder
  • 1 tsp fine sea salt
  • 225g unsalted butter, softened
  • 6 large egg whites, room temperature
  • 180ml whole milk
  • 120g full fat sour cream
  • 2 tsp vanilla bean paste
  • 5 large egg whites (for buttercream)
  • 300g granulated sugar (for buttercream)
  • 450g unsalted butter, cubed and cool
  • 1 tbsp vanilla extract
  • 1 pinch salt

Instructions:

  1. Preheat your oven to 350°F (175°C). Grease three 8-inch round cake pans and line the bottoms with parchment paper.
  2. In a stand mixer bowl, whisk together the cake flour, 400g granulated sugar, baking powder, and 1 tsp sea salt.
  3. With the mixer on low speed, add 225g of softened butter one cube at a time. Continue mixing until the texture resembles coarse, damp sand (Reverse Creaming Method).
  4. In a separate bowl, whisk together 6 egg whites, whole milk, sour cream, and vanilla bean paste. Gradually add this liquid mixture to the dry ingredients, mixing until just combined and smooth.
  5. Divide the batter evenly between the three prepared pans. Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
  6. Allow layers to cool in the pans for 10 minutes, then invert onto wire racks to cool completely before frosting.
  7. To make the buttercream, whisk 5 egg whites and 300g sugar over a double boiler until sugar is dissolved. Whip to stiff peaks, then gradually add 450g cubed butter and vanilla extract until silky.