Cut butter into flour with a pastry blender or fork until crumbly; stir in pecans. Press mixture into a 13- x 9-inch pan or baking dish.
Bake at 350° for 18 to 20 minutes or until lightly browned. Remove pan to wire rack to cool completely.
Beat cream cheese and powdered sugar at medium speed with an electric mixer until fluffy. Fold in whipped topping. Spread cream cheese mixture evenly over cooled crust.
Beat pudding mixes and milk in a large bowl at medium speed with an electric mixer 2 minutes. Pour evenly over cream cheese mixture in pan. Cover and chill 2 hours or up to 3 days. Serve pudding in individual bowls with desired toppings.