Preheat oven to 350°F and prepare two 9-inch cake pans. Whisk flour, baking powder, and salt. Beat butter and sugar until creamy. Add eggs one at a time, then vanilla. Alternate adding dry ingredients and milk. Fold in sour cream. Divide batter into pans. Bake 22–25 minutes. Cool completely before frosting.
Notes
Use room-temperature ingredients for best texture. Avoid overmixing to keep crumb soft.