Smash Cake

Ingredients

• 1/3 cup buttermilk , room temperature
• 2 large egg yolks plus 1 large white, room temperature
• 3 tablespoon sunsalted butter , melted and cooled
• 1 tablespoon can ola oil
• 3/4 teaspoon vanilla extra ct
• 1/2 cup (\1 1/2 ounce s1/99 grams) granulated sugar
• 3/4 cup (3 ounce s1/85 grams) cake flour
• 1/2 teaspoon baking powder
• 1/8 teaspoon baking soda
• 1/4 teaspoon salt
• 20 tablespoon s (\1 1/2 sticks) unsalted butter , each stick cut into quart ers and softened
• 2 tablespoon sheavy cream
• 2 teaspoon svanilla extra ct
• 1/8 teaspoon salt
• 2 1/2 cup s (10 ounce s1/283 grams) confectioners' sugar

Instructions

1. For the cake: Adjust oven rack to middle position and heat oven to 350 degrees. Grease two 6 ­inch round cake pans, line with parchment paper, grease parchment, and flour pans. Whisk buttermilk, egg yolks, butter, oil, and vanilla together in bowl.
2. Using stand mixer fitted with whisk attachment, whip egg white on medium ­low speed until foamy, about 1 minute. Increase speed to medium ­high and whip white to soft, billowy mounds, about 1 minute. Gradually add 2 tablespoons granulated sugar and beat until glossy, stiff peaks form, 1 to 2 minutes; transfer to separate bowl.
3. Return now empty bowl to mixer.
4. Add flour, baking powder, baking soda, salt, and remaining 6 tablespoons granulated sugar, and mix on low speed for 15 seconds to combine.
5. With mixer running, gradually add buttermilk mixture and continue to mix until almost combined (a few streaks of dry flour will remain), about 15 seconds.
6. Scrape down bowl, then mix on medium ­low speed until smooth and fully incorporated, 10 to 15 seconds.
7. Using rubber spatula, stir one ­third of egg whites into batter. Gently fold remaining egg whites into batter until no white streaks remain. Divide batter evenly between prepared pans and smooth tops with rubber spatula. Gently tap each pan on counter to release air bubbles. Bake cakes until toothpick inserted in center comes out clean, 16 to 18 minutes, rotating pans halfway through baking.
8. Let cakes cool in pans on wire rack for 10 minutes. Remove cakes from pans, discarding parchment, and let cool completely on rack, about 1 hour. (This is a good time to make your frosting!).
9. For the frosting: Using stand mixer fitted with paddle, beat softened butter, cream, vanilla, and salt on medium ­high speed until smooth, about 1 minute.
10. Reduce speed to medium ­low, slowly add confectioners’ sugar, and beat until incorporated and smooth, about 4 minutes. Increase speed to medium ­high and beat until frosting is light and fluffy, about 5 minutes.
11. Place 1 cake layer on platter. Spread ½ cup frosting evenly over top, right to edge of cake. Top with second cake layer, press lightly to adhere, then spread ½ cup frosting evenly over top. Spread remaining 1½ cups frosting evenly over sides of cake. To smooth frosting, run edge of offset spatula around cake sides and over top. Decorate as desired. Serve.