Preheat the oven to 300 degrees F (150 degrees C). Coat a 9x13-inch baking dish with cooking spray.

Beat 1/4 cup confectioners’ sugar and margarine together in a medium bowl until creamy. Mix in 1 cup pecans and flour until well combined; press into the prepared dish.

Bake in the preheated oven until very lightly browned, about 15 minutes. Cool completely.

Beat cream cheese and remaining 1 cup confectioners’ sugar together in a large bowl until well combined; fold in 1/2 of the whipped topping until incorporated. Spread over cooled crust.

Stir milk and pudding mix together in a separate bowl until well combined; allow to set up slightly. Spread over cream cheese layer; top with remaining whipped topping and sprinkle with remaining 1/8 cup pecans. Store in the refrigerator.