For a variation on the classic lemon cake, substitute this recipe for the lemon frosting. This makes enough glaze for the four-layer cake or the two 13- x 9-inch cakes. Combine chocolate and whipping cream in a large glass bowl. Microwave at Medium-High (50% power) 3 1/2 minutes. Remove and whisk or stir until chocolate melts and mixture is blended, 1 to 2 minutes. If chocolate isn't melted, microwave again at 50% power 30 to 60 seconds; stir briskly. Whisk or stir in butter. Set aside 10 to 15 minutes or until mixture has cooled to a spreading consistency.
