4 Tablespoons butter or margarine
3 cups milk
1 teaspoon vanilla extract
1 (1 ounce) square unsweetened chocolate
In a small saucepan, combine butter, milk, vanilla extract and chocolate. Bring to a slow simmer, stirring constantly, until mixture is thickened. Remove from heat and stir in sugar. Cool slightly. Let cool. Divide into 12 cups and fill each cup with 1/2 cup frosting.
To make the frosting, beat butter, chocolate and vanilla together until frosting is melted. Pour into individual serving bowls and chill in refrigerator.