- 1 stick unsalted butter, softened
- One 8-ounce container mascarpone cheese, softened
- 3 cups confectioners' sugar, sifted
- 1 teaspoon pure vanilla extract
- In a bowl, beat the butter until smooth. Beat in the mascarpone cheese until combined. Add the sugar and vanilla and beat until smooth. Refrigerate the filling until it is slightly firm, about 2 hours.
The mascarpone filling can be refrigerated for up to 1 day; let stand at room temperature until softened slightly before using.