White Velvet Cake with White Chocolate Buttercream Frosting

Directions

• 1. Step 1Make cake: Preheat oven to 325°F. Line 4 (8-inch) round cake pans and 3 (6-inch) round cake pans with parchment paper. Lightly grease pans and parchment.
  2. Step 2Beat butter, sugar, baking powder, baking soda, and salt with an electric mixer on low speed until combined. Increase mixer speed to medium, and beat until light and fluffy, 4 to 6 minutes, scraping the sides as needed.
     Beat in egg whites, 1 at a time, beating until incorporated after each addition. Beat in vanilla. Stir together buttermilk and oil in a separate bowl.
  3. Step 3Transfer butter mixture to a very large mixing bowl. Gently fold flour and buttermilk mixture into butter mixture, in thirds, beginning and ending with the flour mixture. Transfer batter to prepared pans (about 1 1/3 cups in each 6-inch and 2 1/2 cups in each 8-inch pan).
  4. Step 4Bake, in 2 batches, until a toothpick inserted in center comes out clean, 25 to 30 minutes for 6-inch cakes and 30 to 35 minutes for 8-inch cakes. Cool in pans on wire racks 10 minutes; remove cakes to wire racks and cool completely.
  5. Step 5Make buttercream frosting and assemble: Meanwhile, melt white chocolate in a double boiler or on 50% power in microwave, stirring every 60 seconds, until smooth. Cool to room temperature, about 30 minutes.
  6. Step 6Beat butter with an electric mixer on medium speed until creamy, 1 to 2 minutes. Reduce speed to low and gradually
     beat in confectioners’ sugar until incorporated. Beat in vanilla
     and salt. Increase speed to medium-high, and beat until fluffy, scraping the sides as needed, 1 to 2 minutes. Reduce speed to low and slowly beat in chocolate. Increase speed to medium and beat until smooth, about 1 minute.
  7. Step 7Place 1 8-inch cake layer on
     a plate. Top with 3/4 cup buttercream, spreading to the edge. Repeat two more times with cake and buttercream. Top with fourth cake layer. Spread 2 cups buttercream on top and sides of cake, smoothing frosting. Place 1 small cake layer on a plate. Top with
     1/2 cup buttercream. Repeat once with cake and buttercream. Top with third cake layer. Trim top
     1/2 inch of cake using a serrated knife to flatten, if necessary. Spread 1 1/2 cups buttercream on top and sides of cake, smoothing buttercream. Chill 30 minutes.
  8. Step 8Divide remaining buttercream among 2 bowls. Tint 1 bowl
     with pink food coloring to desired color, stirring until fully combined. Remove about 1 tablespoon white frosting to a small bowl, and tint remaining second bowl with green food coloring
     to desired color, stirring until fully combined. Leave remaining buttercream white.
  9. Step 9Place larger cake on serving plate or cake stand. Spread a small amount of buttercream in center, and top with small cake. Use a palette knife or small offset spatula, smear pink and white frosting on cake to resemble flower petals. Place a few sugar pearls in the center of some of the flowers. Smear a few small green leaves throughout.