Ingredients:

  • 375g cake flour
  • 400g granulated sugar
  • 10g Dutch-processed cocoa powder
  • 1 tsp baking soda
  • 1 tsp salt
  • 240ml buttermilk, room temperature
  • 240ml vegetable oil
  • 115g unsalted butter, melted
  • 2 large eggs, room temperature
  • 1 tsp distilled white vinegar
  • 1 tbsp vanilla extract
  • 2 tsp royal purple gel food coloring
  • 225g unsalted butter, softened
  • 500g powdered sugar, sifted
  • 45ml heavy cream
  • 2 tsp vanilla bean paste
  • 1 pinch salt

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and line two 8-inch round cake pans with parchment paper.
  2. Sift together the cake flour, granulated sugar, cocoa powder, baking soda, and 1 tsp salt in a large bowl.
  3. In a separate medium bowl, whisk together the buttermilk, vegetable oil, melted butter, eggs, vinegar, vanilla extract, and purple gel food coloring until well combined.
  4. Gradually add the wet ingredients to the dry ingredients. Mix on medium speed using a stand mixer with a paddle attachment until the batter is smooth and the color is uniform.
  5. Divide the batter evenly between the prepared cake pans. Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.
  6. Cool cakes in the pans for 10 minutes before transferring to a wire rack to cool completely.
  7. To make the frosting, beat 225g softened butter on medium-high speed until creamy. Gradually add powdered sugar, heavy cream, vanilla bean paste, and a pinch of salt. Beat on high until light and fluffy.
  8. Level the cooled cakes if necessary. Place one layer on a serving plate, cover with frosting, top with the second layer, and frost the top and sides of the cake.