Instructions

• Let the 1/4 cup butter soften on the counter until soft but still holding its shape (about 30–60 minutes).
• Put 2 cups powdered (icing) sugar, the softened butter, 1 teaspoon pure vanilla extract, and 1 tablespoon milk into a large mixing bowl.
• Using an electric hand mixer, start on low and mix until the dry sugar is incorporated and no large lumps remain. Scrape down the bowl and beat on medium for 30–60 seconds until the mixture is smooth and creamy.
• If the frosting is too thick, add additional milk (from the "extra as needed") 1/4 teaspoon at a time, mixing briefly after each addition, until the frosting is spreadable but still holds its shape. Do not use water.
• Fold in 2 tablespoons (or to taste) rainbow sprinkles with a spatula or spoon until evenly distributed.
• Frost cookies or cupcakes as desired.
• If not using right away, store the frosting covered in a cool place (refrigerator recommended). Bring to room temperature and stir before using if chilled.