Sprinkles are located all over these funfetti cupcakes. They are included in the batter and baked inside these vanilla-flavored treats, and rolled onto the frosting to coat the edges – just enough to give you that extra “sugar rush” when biting into them. The batter itself is fairly simple; it’s a mix of cake flour, butter, salt, egg whites, milk, vanilla extract, sugar and baking powder, not to mention the rainbow sprinkles, of course. The frosting is an equally simple vanilla buttercream, which makes the sprinkles stand out just a bit more in contrast.
Source The Cake Blog