Combine Flour,Sugar,Cocoa,and Butter. Use two knives or pastry blender.(pastry blender works best.) Mixture will be crumbley. Press firmly into a 13x9 pan. Bake at 350 for 15 minutes.
In saucepan combine both pkgs of semi-sweet Choc Chips,Vanilla, Milk,and Nuts if using. Stir until well melted. Pour over prepared crust.
Sprinkle Milk Chocolate chips on top and press on to top of filling. Bake for 20 minutes. Cool at least 10 minutes(will be hard to wait after smelling this bake! Cut into bars and enjoy,I cut into very small bars,this is very rich,and ya might overdose yourself on CHOCOLATE! Enjoy, Sassycook.