– 4 ½ cups all-purpose flour – 4 ½ teaspoons baking powder – ¾ teaspoon salt – 1 ½ cups unsalted butter , at room temperature – 1 ½ cups sugar – 3 large eggs – 5 teaspoons vanilla extract For the frosting: – 5 cups confectioners' sugar , sifted – ⅓ cup (5 ⅓ Tablespoons) unsalted butter, melted – 1 Tablespoon vanilla extract – 7 Tablespoons milk (plus more, as needed) – Food coloring , optional – Sprinkles (optional)