With an electric mixer, beat together the butter, orange juice concentrate, zest, icing sugar custard powder and milk until smooth.
Here is the ingredient list for the base and filling of the original version of this recipe as written in 2011.
For the Base Layer
1/2 cup butter
1/4 cup sugar
5 tbsp cocoa
one beaten egg
1 3/4 cups graham cracker crumbs
3/4 cup fine or medium unsweetened coconut
1/2 cup finely chopped walnuts
For the the Orange Frosting Filling
1/2 cup butter
2 tsp pure mint extract
2 cups icing sugar i.e., powdered sugar or confectioners sugar
Zest of one orange finely minced
2 tablespoons frozen Orange juice concentrate