Preheat oven to 350°F (175°C). Combine flour, butter, and pecans. Press into a 9×13-inch dish and bake for 15 minutes.
Let the baked crust cool completely before adding the cream cheese layer.
Beat softened cream cheese with powdered sugar until smooth. Fold in half of the whipped topping, then spread over the cooled crust.
Whisk the pudding mix with cold milk until thick. Spread over the cream cheese layer.
Top with the remaining whipped topping. If desired, garnish with chocolate curls or chopped nuts.
Chill for at least 4 hours or overnight before slicing.
Serve cold.