7. Make the chocolate ganache: in a microwave-safe bowl combine 1/4 cup heavy cream and 1 tablespoon cubed butter. Heat in the microwave for 1 minute, then stir. If butter is not fully melted or mixture is not hot, continue heating in 30-second intervals, stirring after each, until hot and combined. Add the 4 oz. chopped semi-sweet baking chocolate and stir until the chocolate is melted and the ganache is smooth. If desired, stir in 1 teaspoon corn syrup (optional) for extra shine.
10. Refrigerate the assembled brownies for at least 2 hours before cutting. Store any leftovers in the refrigerator.