1. Crust Layer:
Stir together butter, flour, sugar, and chopped pecans/walnuts in a mixing bowl. (A fork works really well to get everything mixed together.)
Press into an ungreased 9x13 baking dish and bake 15-20 minutes at 350° F, or until a light golden brown. Remove from oven and set aside to cool.
2. Cream Cheese Layer:
Beat together cream cheese and powdered sugar until creamy and smooth. Spread over cooled crust.
3. Pudding Layer:
In another mixing bowl, whisk together pudding mixes, lemon juice, and milk for 3-5 minutes. Allow to sit for 5 minutes to thicken up. Spread on top of the cream cheese layer; cover and place in the fridge for 1 hour.
Spread whipped topping over the pudding layer. Cut into 18-24 pieces (depending on how large or small you cut them) and garnish with fresh lemon zest. Keep leftovers covered and stored in the fridge.