It flavors really well, so feel free to experiment. Maybe use bubblegum, for example? :)
This is my go-to vanilla frosting recipe (although I'd almost always prefer cream cheese frosting or whipped cream frosting).
I usually use this one if I need my frosting to hold up well in the heat, or for transportation, or just over a several day period.
Marshmallow Buttercream Frosting
Recipe from Baked Bree
-1 cup softened UNSALTED butter (2 sticks)
-1 (7-ounce) jar marshmallow creme
-2 cups powdered sugar
-1 teaspoon vanilla (or other extract)
Cream butter until light and fluffy. Add marshmallow creme. Whip for 2 minutes.
Add powdered sugar and mix for 30 seconds at low speed, then continue to beat on medium/high for 2 minutes longer.
Add vanilla or other extract and mix until combined.