Preheat your oven to 350. Line 2 9inch round cake pans with parchment paper. Mix your cake mix according to box directions and bake for 35 minutes or until done and cakes spring back when pressed lightly.
Remove from oven and let cool in pans. Mix and cook your pudding custard until thick and bubbly. Remove from heat and cover with plastic wrap right on surface so no skin will form on surface and let cool.
In a small bowl add coffee flavoring to topping and set aside. On a cake plate place 1st cake layer face down after parchment paper is removed. Spoon thick custard to edges. Do the same with the second layer only cake will face upward.
Your topping can be as thick or loose as you wish. I let some of topping run over the sides. Refrigerate for 2 hours or until custard and topping have set well. Cover any leftovers with foil or a cake lid and keep refrigerated.