Preheat oven to 350°F (175°C). Grease and flour two 8- or 9-inch round cake pans.

In a bowl, whisk together cake flour, sugar, baking powder, and salt.

In a large bowl, cream butter and sugar until light and fluffy.

Add vanilla extract and mix until combined.

Whip egg whites in a separate bowl until stiff peaks form.

Alternate adding dry ingredients and milk to the butter mixture, beginning and ending with dry ingredients. Mix on low speed.

Gently fold in the whipped egg whites.

Divide batter evenly between pans and smooth the tops.

Bake until a toothpick inserted in the center comes out clean.

Cool in pans for 10 minutes, then transfer to a wire rack to cool completely before frosting.