Aunt Jane'S Caramel Icing
["1/2 c. butter, melted", "1 c. brown sugar", "1 c. white sugar", "1/2 c. Pet milk"]
["Mix together well.", "Let boil slowly.", "Set pan in cold water, adding one teaspoon vanilla.", "Stir until thick and spread on cake."]
["butter", "brown sugar", "white sugar", "Pet milk"]