Preheat oven to 350°F (175°C) and grease two 9-inch round cake pans.
Whisk flour, baking powder, and salt in a bowl.
Beat butter and sugar together until light and fluffy.
Add eggs one at a time, then mix in vanilla extract.
Alternate adding dry ingredients and milk, beginning and ending with dry ingredients.
Fold in sour cream gently until just combined.
Divide batter evenly between pans and smooth tops.
Bake 25–30 minutes until a toothpick inserted in the center comes out clean.
Cool completely before frosting.