01 - In a large mixing bowl, beat the softened butter using a hand mixer or stand mixer until creamy and pale, about 2 minutes.
02 - Add sifted powdered sugar, 1 cup at a time, mixing on low speed until fully incorporated after each addition.
03 - Pour in the milk and vanilla extract. Beat on medium-high speed until the frosting is smooth and fluffy, about 2 to 3 minutes.
04 - Gently fold 3/4 cup of Fruity Pebbles cereal into the frosting using a spatula until evenly distributed throughout.
05 - Spread or pipe the frosting onto completely cooled cupcakes or cakes.
06 - Sprinkle the remaining 1/4 cup of Fruity Pebbles cereal on top just before serving to maintain maximum crunch.