For a simple chocolate glaze, microwave 6 ounces of semi-sweet chocolate and 1 tub of frozen whipped topping in a microwave safe bowl on high for one to two minutes, stirring every 30 seconds until well-combined and free of lumps.
Alternatively, in a 2-cup, microwave-safe measuring cup, microwave for one minute on medium power 1/2 cup of semisweet chocolate chips with 2 tablespoons each of butter and corn syrup. Stir after the mixture has heated. If the glaze has not completely melted, continue heating for up to one minute longer, stirring after 30 seconds.
For an easy stove-top chocolate ganache glaze, bring 1/2 cup heavy whipping cream just to a boil in a small saucepan. Pour the hot cream over 4 ounces of roughly cut or shredded semisweet chocolate, and whisk until thoroughly melted together. Cool the glaze long enough to thicken it, but not so long that it becomes difficult to pour.
To make a chocolate glaze without using heat, sift together 4 tablespoons cocoa powder and 1 1/2 cups powdered (confectioner's) sugar. Mix together 2 tablespoons milk and 2 teaspoons vanilla extract. Slowly pour the wet ingredients over the dry ingredients, stirring constantly until well-combined and thin enough to be poured over cake.