01 - Preheat oven to 350°F. Lightly grease a 9x13 inch baking dish or line with parchment paper.
02 - In a medium mixing bowl, combine the all-purpose flour, softened butter, and powdered sugar. Blend with a fork or pastry cutter until the mixture resembles coarse crumbs. Press the dough firmly and evenly into the bottom of the prepared baking dish.
03 - Bake for 18 to 20 minutes, or until the crust is lightly golden around the edges. Remove from the oven and allow to cool completely on a wire rack.
04 - Using an electric mixer, beat the softened cream cheese and powdered sugar on medium speed until completely smooth and creamy. Gently fold in 1 cup of thawed 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, cold milk, and lemon zest if using. Whisk vigorously for about 2 minutes until the pudding thickens. Let it rest for 5 minutes to fully set, then spread evenly over the cream cheese layer.
06 - Spread the remaining 1 1/2 cups of whipped topping evenly over the lemon pudding layer, smoothing the surface with a spatula.
07 - Sprinkle lemon zest over the top for garnish if desired. Cover with plastic wrap and refrigerate for at least 2 hours, preferably 3 or more, until fully chilled and set. Slice into squares and serve cold.