Add flour, pecan, and melted butter with a medium mixing bowl and stir until combined and moistened. Pour the crust into a 9-inch x 13-inch baking dish and press firmly in an even layer to create the crust.
Bake for 15 minutes. Remove from oven and cool completely before adding pie filling.
While crust is cooling, mix cream cheese, powdered sugar, white chocolate pudding, and 8 ounces of Cool Whip in a large mixing bowl until smooth.
Once the crust is completely cooled, spread the cream cheese layer evenly over the crust.
Add the chocolate instant pudding mix and milk to a medium mixing bowl. Stir together with a whisk for 2 minutes. Pudding with be smooth and thickened. Spread the chocolate pudding over the cream cheese layer so it's covered completely.
Top your mud pie with 16 ounces of Cool Whip. Spread it out all over the pie so it reached the corners of the pan. Sprinkle extra chopped pecan and chocolate shavings (from your chocolate bars) over the whipped topping. Cover and refirgerate until ready to serve.
Using the white chocolate pudding gives this pie a creamer smoother taste that goes great with the chocolate pudding layer.