Preheat oven to 350°. Prepare Truffle Fudge Brownie Mix according to package directions. Divide among greased mason jars. Place jars on a foil-lined baking sheet.
Bring 2 cups water to a boil in a small saucepan; add frosting. Reduce heat to low; cook, stirring frequently, until smooth. Slowing pour frosting over brownie batter in mason jars. Do not stir. Jars will be very full.
Carefully transfer to oven. Bake 35 minutes or until edges are bubbly and brownie is done in the center. Cool slightly before serving. Serve garnished with whipped cream and drizzled with Creamy Caramel Sauce, if desired. Makes 8 servings.