1. Preheat oven to 325 degrees F. Lightly grease two 8 x 1-1/2-inch round baking pans; line bottom of each with waxed paper. Grease the waxed paper and set pans aside. Prepare brownie mix according to package directions; divide batter and spread into prepared pans.
2. Bake for 25 minutes. Cool in pan on wire rack for 10 minutes. Loosen edges, invert, and carefully remove brownie from pan. Peel off waxed paper. Cool completely. Wrap each of the brownies in plastic wrap. Place one of the brownie rounds in an airtight freezer container and freeze for up to 2 months. Store remaining brownie at room temperature for several hours or overnight while berry-ice cream layer is being frozen.
3. Line an 8 x 1-1/2-inch round pan with plastic wrap, allowing excess to extend over edges; set aside. In a large mixing bowl stir ice cream just to soften. Carefully fold in 1 cup of the berries. Spread berry-ice cream mixture evenly in prepared pan. Cover and freeze for 4 to 24 hours.
4. To serve, place one brownie round on serving plate. Lift ice cream and plastic wrap from pan. Invert ice cream layer onto brownie; peel off plastic wrap. Top with the remaining 1-1/2 cups of berries. Drizzle with chocolate topping or raspberry syrup. Let dessert stand for 15 minutes before serving to soften slightly.