To make the crust, combine flour, nuts, and butter with a fork and then use your hands to squish it together until well combined. Press in the bottom of a lightly greased 9x13" pan (just grease the bottom). Bake at 350 degrees Fahrenheit for about 13-15 minutes. Let cool completely.
While the crust is baking and cooling, prepare the cream cheese layer by mixing together cream cheese, powdered sugar and cool whip with an electric mixer. Spread over cooled crust.
Prepare two packages of instant chocolate pudding mix according to package directions. Pour over the cream cheese layer and place in the fridge so the pudding can set up.
Just before serving, spread the remainder of the cool whip tub over the top, sprinkle with chopped nuts, chocolate shavings or mini chocolate chips, toffee or candy bar bits and serve.