Black Walnut Gold Filling Cake
["1 box German chocolate cake mix", "1 stick butter", "4 eggs", "4 Tbsp. flour", "black walnuts to taste", "1 tsp. black walnut flavoring", "2 c. sugar", "1 (12 oz.) can evaporated milk", "1 1/2 tsp. vanilla", "coconut to taste"]
["Mix cake and bake as directed on box for 3 round cake pans. Mix remaining ingredients listed to use as icing for each layer and on sides of cake.", "Make sure to cool cake before frosting."]
["chocolate cake", "butter", "eggs", "flour", "black walnuts", "black walnut flavoring", "sugar", "milk", "vanilla", "coconut"]