Creamy Blender Chocolate Frosting

6 (1 ounce) squares unsweetened baking chocolate
1 cup evaporated milk
1 teaspoon vanilla extract
1 1/2 cups granulated sugar
6 tablespoons butter or margarine

Cut chocolate into small pieces. Put all of the ingredients into a blender. Cover. At low speed, blend until larger pieces are chopped. Stop motor and stir. Blend at high speed until frosting becomes thick and creamy.

Makes 3 cups frosting.