Preheat the oven to 350°F and spray a 9 x 13 inch baking dish with cooking spray. In a small mixing bowl, cut the butter into the flour, then add the pecans. Press firmly onto the bottom of the baking dish.
Bake for 22-25 minutes until lightly golden. Cool completely.
In a medium mixing bowl, whip together 2  oz softened cream cheese, 1 cup of powdered sugar and vanilla extract until creamy and smooth. Fold in 1  oz whipped topping by hand. Spread over the cooled crust.
In the same bowl, whip together both packages of fudge instant pudding mix and 3 cups of half & half or whole milk. Whip until thickened.
Spread over the cream cheese layer.
Frost with the remaining  oz thawed whipped topping.
Sprinkle the top with grated chocolate.
Chill for at least 4 hours before cutting.