Chocolate Frosting
["1 1/2 c. sugar", "4 1/2 Tbsp. cornstarch", "3 (1 oz.) sq. unsweetened chocolate, grated", "dash of salt", "1 1/2 c. boiling water", "4 1/2 Tbsp. margarine", "1 1/2 tsp. vanilla flavoring"]
["Mix sugar and cornstarch; add chocolate and salt.", "Add water. Cook in heavy saucepan until mixture thickens.", "Remove from heat. Add butter and vanilla.", "Spread on cake while hot."]
["sugar", "cornstarch", "unsweetened chocolate", "salt", "boiling water", "margarine", "vanilla flavoring"]