under 30 minutes
1 cup unsalted butter, softened
1 jar (7 ounce size) marshmallow cream
1 cup confectioners' sugar
1 teaspoon vanilla extract
In a medium mixing bowl, beat butter with mixer at medium speed until creamy. Beat in marshmallow cream. When well blended, beat in confectioners' sugar and vanilla.
Increase speed and beat for 3 or 4 minutes, until fluffy.