01 - Preheat oven to 350°F. Lightly grease a 9x13 inch baking dish or line with parchment paper.
02 - In a medium bowl, combine the all-purpose flour, softened butter, and powdered sugar. Blend with a fork or pastry blender until the mixture resembles coarse crumbs. Press the mixture evenly and firmly into the bottom of the prepared baking dish to form a uniform crust layer.
03 - Bake for 18 to 20 minutes, or until the edges are lightly golden. Remove from the oven and set aside to cool completely before adding subsequent layers.
04 - Using an electric mixer, beat the softened cream cheese and powdered sugar on medium speed until completely smooth and free of lumps. Gently fold in the whipped topping until evenly combined. Spread the mixture in a smooth, even layer over the fully cooled crust.
05 - In a separate bowl, whisk together both packages of instant lemon pudding mix and the cold milk for approximately 2 minutes until the mixture thickens. Add lemon zest if using. Allow the pudding to rest for 5 minutes until fully set, then spread it evenly over the cream cheese layer.
06 - Spread the remaining whipped topping evenly over the lemon pudding layer, covering the entire surface. Use a spatula to create smooth, even coverage.
07 - Sprinkle lemon zest over the top for garnish, if desired.
08 - Refrigerate for at least 2 hours, preferably 3 or more, until all layers are firmly set. Slice into 12 portions and serve chilled.