Recipe(tried): Baker's One Bowl Chocolate Frosting (microwave) (I'm 99% sure this is it)

This is the recipe I used, I found it on the net but it only called for 4 squares of chocolate. I'm positive the one I used called for 8 squares (the whole package). I used 8 squares, after I checked the recipe serveral times because it seemed like a lot. It was wonderful! I used evaporated skim milk for the milk and real butter for the shortening.

BAKER'S ONE BOWL CHOCOLATE FROSTING

8 squares BAKER'S Unsweetened Baking Chocolate (I used semi-sweet chocolate squares)
1 pkg. (16 oz.) powdered sugar (about 4 cups)
1/2 cup (1 stick) butter or margarine, softened
2 tsp. vanilla
1/3 cup milk

Microwave chocolate in large microwaveable bowl on HIGH 1-1/2 minute, stirring every 30 sec. Stir until chocolate is completely melted. Cool 5 minutes or to room temperature.

Add sugar, butter and vanilla. Gradually add milk, beating with electric mixer on low speed until well blended. If frosting becomes too thick, beat in additional milk by teaspoonfuls until frosting is of spreading consistency.

Makes enough to frost tops and sides of 2 (8- or 9-inch) cake layers, top and sides of 13x9-inch cake, tops of 3 (8- or 9-inch) cake layers or 24 cupcakes.