5 egg whites
1 cup milk, divided
2 teaspoons vanilla
3 cups sifted cake flour
1 ½ cups granulated sugar
1 tablespoon plus 1 teaspoon baking
powder
¾ teaspoon salt
¾ cup unsalted butter, softened
(1½ sticks)
Preheat oven to 350 degrees. Combine egg whites, ¼ cup milk and vanilla in medium bowl. Set aside.
Combine flour, sugar, baking powder and salt in large mixing bowl of electric mixer; mix on low speed for 30 seconds. Add butter and remaining ¾ cup milk. Beat on low speed until dry ingredients are moistened. Increase to medium speed; beat 1½ minutes. Gradually add egg white mixture in 3 batches, beating 20 seconds after each addition.
Grease two 9-inch cake pans; line bottoms with parchment or wax paper, and grease paper and sides of pan. Sprinkle lightly with flour. Pour batter into pans. Bake until tester inserted in centre comes out clean and cake springs back when touched, 25 to 35 minutes.
Let cool in pans for 10 minutes. Loosen sides of cakes and invert onto greased cooling racks. Cool completely before filling and frosting cake. Makes 12 servings.