Preheat oven to 375 degrees F. Line a 12-cup standard muffin tin with paper liners; set aside.

In a large bowl, combine flour, baking powder and salt. campaignIcon Coupons

In a medium bowl, whisk together milk, egg whites and vanilla.

In the bowl of an electric mixer fitted with paddle attachment, beat butter and sugar on medium speed until light and fluffy, about 2-3 minutes. With mixer on low speed, add dry ingredients and milk mixture alternately in 3 parts, beginning and ending with dry ingredients, beating just until incorporated. Add rainbow jimmies and stir using a rubber spatula just until moist.

Scoop the batter evenly into the muffin tray. Place into oven and bake for 15-18 minutes, or until a tester inserted in center comes out clean. Remove from oven and cool completely on a wire rack before frosting.

In the bowl of an electric mixer fitted with the paddle attachment, beat butter and confectioners’ sugar on medium speed until light and fluffy, approximately 1-2 minutes. With the mixer on low speed, gradually add heavy cream and vanilla, beating just until incorporated. Increase speed to medium high and beat until frosting is light and fluffy, approximately 1-2 minutes.

Use a small offset spatula or a pastry bag fitted with a decorative tip to frost cupcakes, garnished with Fruity Pebbles, if desired.