Melt the butter in 1-quart saucepan over medium heat. Continue cooking, stirring occasionally and watching closely, until the butter turns golden brown, 5 to 7 minutes. Remove from the heat. Cool completely. Combine the browned butter, confectioners' sugar and vanilla in a medium bowl. Beat at medi-um speed, gradually adding enough heavy cream for the desired spreading consistency. Yield: filling for one 9-inch cake