- 1 pound unsalted butter (at room temperature)
- 2 cups confectioners' sugar
- 1/2 teaspoon pure vanilla extract (optional)
- 1 (16 ounce) tub marshmallow cream (such as Marshmallow Fluff®)
- In a large mixing bowl, beat the butter until creamy.
- Beat in one-fourth of the sugar until fluffy, then repeat with the remaining sugar.
- Beat in the vanilla, then stir in the marshmallow cream until well blended.