Preheat the oven to 350 degrees.
In a medium bowl, combine the melted butter, flour, and 3/4 cup nuts.
Press the mixture into a 9 x 13 inch baking dish.
Bake for 10 to 12 minutes, until a firm crust forms; let cool.
In a medium bowl, whisk together the pudding mix and milk until thickened; set aside.
In another medium bowl, combine the cream cheese, powdered sugar, and half of the whipped topping; mix well.
Using a wet table knife, spread the cream cheese mixture over the top of the cooled crust.
Spoon the chocolate pudding mixture over the top of the cream cheese mixture, then top with the remaining whipped topping.
Sprinkle the remaining 1/4 cup walnuts over the top.
Cover and chill for at least 6 hours, or overnight.
Store any leftovers in the refrigerator.