Adult: Set the oven rack in the middle position. Preheat the oven to 350 deg F.

Child: Line muffin pans with cupcake liners.

Adult & Child together: Measure and pour the milk, egg whites, and vanilla extract into a medium bowl and mix with a fork until blended.

Adult & Child together: Measure and mix the flour, sugar, baking powder, and salt in the bowl of an electric mixer at the lowest speed. Add the butter pieces; continue beating on low speed until the mixture resembles moist crumbs, with no powdery ingredients remaining, about 1 minute.

Adult & Child together: Add all but 1/2 cup of the milk mixture to the crumbs and beat at medium speed for 1 minute. Add the remaining 1/2 cup of the milk mixture and beat 30 seconds longer. Stop the mixer and scrape the sides of the bowl. Return the mixer to medium speed and beat about 20 seconds longer.

Adult & Child together: Pour the batter into muffin cups so that the cups are about 80% full.

Adult: Bake the cupcakes for 17 to 20 minutes. Insert a toothpick into the center of a cupcake; if it comes out clean, it is done. Transfer the muffin pans to wire cooling racks or away from the hot oven. Let them cool for 10 minutes. Place your cupcakes onto a rack or plate to continue to cool. Be sure to cool the cupcakes completely before frosting, about 1 hour.