Prep oven and pan. Position a rack in the center of the oven preheat the oven to 350°F (177°C). Line two cupcake pans with paper liners. Set aside.
Combine dry ingredients. In a medium mixing bowl, whisk together flour, baking powder and salt until evenly combined. Set aside. 1 ½ cup (180 g) all purpose flour 1 ½ teaspoons baking powder ¼ teaspoon salt
Combine wet ingredients. In a separate mixing bowl, whisk together the melted butter and sugar. Whisk in the eggs and egg white until incorporated. Whisk in the vanilla. 8 tablespoons (1 stick, 113 g) unsalted butter 1 cup (200 g) granulated sugar 2 large eggs 1 egg white 1 tablespoon vanilla extract
Alternate dry ingredients and milk. Alternate adding the dry ingredients and milk into the wet ingredient mixture, beginning and ending with the flour mixture. I do this in 3 additions (flour, milk, flour, milk, flour). Stir just until the last of the flour has been mixed in. Do not overmix. ½ cup (120 mL) whole milk
Bake. Divide the batter between the prepared paper liners, filling each about 3/4 of the way full. Bake 18-22 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool in the pans 5-10 minutes, then transfer to a cooling rack to cool completely.