Preparation Prepare barbecue (medium heat). Butter 1 side of each bread slice. Arrange 4 bread slices, buttered side down, on baking sheet; spread each with 1 tablespoon preserves. Arrange 8 berries over preserves on each slice. Sprinkle chocolate evenly over each, leaving 1/2-inch border. Spread mascarpone over plain side of remaining 4 bread slices, leaving 1/2-inch border. Place bread slices, mascarpone side down, atop each chocolate-topped bread slice. Sprinkle buttered side of sandwiches with 1 teaspoon brown sugar; press lightly to adhere. Grill each sandwich until chocolate melts and bread is golden, about 3 minutes per side. Transfer to work surface; cool 5 minutes. Using serrated knife, cut each sandwich in half. Transfer to plates.
Preparation Prepare barbecue (medium heat). Butter 1 side of each bread slice. Arrange 4 bread slices, buttered side down, on baking sheet; spread each with 1 tablespoon preserves. Arrange 8 berries over preserves on each slice. Sprinkle chocolate evenly over each, leaving 1/2-inch border. Spread mascarpone over plain side of remaining 4 bread slices, leaving 1/2-inch border. Place bread slices, mascarpone side down, atop each chocolate-topped bread slice. Sprinkle buttered side of sandwiches with 1 teaspoon brown sugar; press lightly to adhere. Grill each sandwich until chocolate melts and bread is golden, about 3 minutes per side. Transfer to work surface; cool 5 minutes. Using serrated knife, cut each sandwich in half. Transfer to plates.