Preheat the oven to 350°F. In a bowl, combine the flour, softened butter, chopped pecans, and a pinch of salt. Mix until it forms a crumbly texture. Press the mixture firmly into the bottom of a 9x13-inch baking dish.

Bake for 15 minutes or until the crust is light golden brown. Carefully remove from the oven and allow it to cool completely.

Using an electric mixer, beat the cream cheese and powdered sugar together until smooth. Gently fold in half of the whipped topping. Spread this cream cheese layer evenly over the cooled crust.

Chill for about 20 minutes. Meanwhile, whisk together the instant chocolate pudding mix and milk until smooth and slightly thickened.

Pour and spread this pudding mixture over the cream cheese layer. Top with the remaining whipped topping and smooth the surface.

Refrigerate the assembled dessert for at least 2 hours, until fully set. Slice and serve chilled, garnished with additional pecans and chocolate shavings if desired.