Preheat oven to 350°. Spray 3 (9-inch) round cake pans with nonstick baking spray with flour. Set aside.
In a large bowl, beat butter and sugar at medium speed with an electric mixer until fluffy. Add vanilla, beating to combine.
In a medium bowl, sift together flour, baking powder, and salt. Add flour mixture to butter mixture in 3 batches, alternately with buttermilk, beginning and ending with flour mixture.
In another bowl, beat egg whites at high speed with an electric mixer until stiff. Fold in egg whites, one-third at a time. Divide batter evenly among prepared pans.
Bake until a wooden pick inserted in the centers of layers comes out clean, approximately 20 minutes. Let cool in pans for 10 minutes. Remove from pans, and let cool completely on wire racks.
Spread Strawberry Curd evenly between layers. Spread Strawberry Frosting on sides and top of cake. Garnish with fresh strawberries, if desired.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/strawberry-birthday-cake/