This has been a family favorite for over 25 years. It is also known as Robert Redford Dessert or lemon torte dessert. I originally found this in a cookbook from my son's school when he was in elementary school in the 80's. It's always the first thing to go at parties and it's nice because you can make it the night before and the leftovers keep for several days.
Preheat oven to 350 degrees. Lightly spray a 9 x 13 pan with cooking spray. In medium bowl, mix together flour, pecans, and butter to form coarse crumbs. Press firmly into the 9 x 13 pan. Bake in 350 oven for 10-14 minutes until lightly browned. Remove from oven and let cool for 15 minutes or more. You can place this in the freezer while preparing other ingredients.
In the same bowl you used for the crust beat together powdered sugar and softened cream cheese with the electric mixer (it is very important that cream cheese is at room temperature or you will get lumps). After it is fluffy fold in 1/2 tub cool whip mixing lightly until combined.
After crust is completely cooled, spread cream cheese/cool whip mixture over crust. This is tricky so do it in smooth motions. Put in refrigerator while preparing pudding.
To prepare pudding, put both packages of pudding mix in a bowl and whisk in 2 cups cold milk and whip by hand until smooth. Make sure everything is combined well and pudding is very smooth.
Spread pudding over cream cheese layer. Top with remaining cool whip. Chop up a few nuts finely and sprinkle over top. Cool in refrigerator for two hours or overnight covered with plastic wrap.