Preheat oven to 350*F and spray 2 (8-inch) cake pans or 3 (6-inch) cake pans with nonstick spray. Line with parchment paper and spray again.
Whisk together flour, baking powder, and salt. Set aside.
Combine sugar, oil, egg, egg whites, and vanilla bean paste. Mix on medium speed with an electric mixer until blended.
Add half of flour mixture and half of milk. Mix until smooth. Repeat with flour and milk.
Divide cake batter evenly among cake pans. Bake 20-23 minutes or until lightly golden and a toothpick inserted into the center of cake comes out clean.
Let cakes cool completely before frosting.