Combine chocolate morsels and butter in a large microwave-safe bowl. Microwave at high for 2 minutes, stirring once. Stir in condensed milk and the next 3 ingredients. Spoon into a greased 13"x9" pan. Bake at 350 degrees for 24 to 30 minutes. Cool slightly on a wire rack. Spread on chocolate frosting while the brownies are still warm.