This Recipe is from allrecipes.com and makes enough frosting/filling for one cake mix (2 layered cake). However, I usually use 2 cake mixes make a 3 layered cake and extra cupcakes. So, you may want to double or do a one and a half batch.
1 C evaporated milk
1 C white sugar
3 egg yolks beaten with 1 T water
1/2 C margarine
1 t. vanilla extract
1 C chopped pecans
1 C flaked coconut
In a large saucepan, combine evaporated milk, sugar, egg yolks, margarine and vanilla. Cook over low heat, stirring constantly, until thick. Remove from heat and stir in pecans and coconut. Spread on cake while still warm.