01 - Preheat oven to 350°F. Prepare a 9x13 inch baking dish by lightly greasing or lining it.
02 - In a medium bowl, blend flour, softened butter, and powdered sugar until the mixture becomes crumbly. Press evenly into the bottom of the baking dish to form a uniform layer.
03 - Bake for 18–20 minutes, or until the crust is lightly golden. Remove from oven and allow to cool completely before adding layers.
04 - Using an electric mixer, beat softened cream cheese and powdered sugar until smooth and creamy. Gently fold in whipped topping until well combined. Spread the mixture evenly over the cooled crust.
05 - Whisk together the instant lemon pudding mixes and cold milk (add lemon zest if using) for about 2 minutes until thickened. Let sit for 5 minutes to fully set, then spread evenly over the cream cheese layer.
06 - Spread the remaining whipped topping evenly over the lemon pudding layer, smoothing the surface with a spatula.
07 - Garnish with lemon zest if desired. Refrigerate for at least 2 hours, preferably 3 or more, until fully set. Slice into squares and serve chilled.