Prepare brownie mix according to package directions for fudge-like brownies. Spread batter is a greased and floured 9-in baking pan. Bake at 350 for 38-42 minutes or until center springs back when lightly touched. Cool for at least 10 minutes. The longer the better. Invert onto a serving plate, cool completely. In a bowl, stir the melted chocolate and butter until smooth. Spread over brownie layer; refrigerate for 30 minutes. Just before serving, top with whipped cream. Decorate with sprinkles.