8 fluid ounces (1 cup) milk (any type), at room temperature
6 egg whites, at room temperature
½ tablespoon vanilla extract
8⅝ ounces (~2¼) cups cake flour
13⅛ ounces (~1¾ cups) granulated sugar
4 teaspoons baking powder
1 teaspoons salt
6 ounces (3/4 cup / 1½ sticks) unsalted butter, softened at room temperature
Instructions
Pre-heat oven to 350 degrees
Grease and flour a 9x13 baking pan; set aside
Whisk together milk, egg whites and vanilla; set aside
In the large bowl of an electric mixer with paddle attachment, mix cake flour sugar, baking powder, and salt on low speed just until combined
Add butter and beat on low speed just until the mixture looks like wet sand with small clumps; scrape the sides of the bowl with spatula
Add half of milk mixture and beat on medium speed for 1½ minutes only; scrape sides of bowl with spatula and add remaining milk; mix on medium speed for just thirty seconds
Pour cake batter into prepared pan and bake for 32-36 minutes or until a knife comes out clean from center