Sweet Potato Surprise Icing
["1 c. sugar", "2 Tbsp. flour", "3 egg yolks", "1 large can evaporated milk", "1 stick margarine", "1 tsp. vanilla", "1 1/2 c. coconut (small can)"]
["In a large thick saucepan, combine flour and sugar. Blend in slowly egg yolks and milk.", "Add margarine (cut in chunks) and vanilla. Cook over medium heat until thick.", "Stir constantly to prevent scorching (about 12 minutes).", "Remove from heat and add coconut. Beat and cool.", "Spread on cake and allow to set several hours for extra moistness."]
["sugar", "flour", "egg yolks", "milk", "margarine", "vanilla", "coconut"]