01 - Preheat oven to 350°F. Prepare a 9"x13" baking dish.
02 - In a medium bowl, combine flour, softened butter, and powdered sugar. Mix until the texture becomes crumbly, then press the mixture firmly and evenly into the bottom of the baking dish.
03 - Bake for 18 to 20 minutes until the crust is lightly golden. Remove from the oven and let cool completely.
04 - Beat the softened cream cheese and powdered sugar together until smooth and creamy. Gently fold in 1 cup of whipped topping until well combined. Spread the mixture evenly over the cooled crust using an offset spatula.
05 - In a large 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. Spread evenly over the cream cheese layer.
06 - Spread the remaining 2 cups of whipped topping gently and evenly over the lemon pudding layer.
07 - Refrigerate for at least 2 hours, or until the layers are fully set and firm.
08 - Garnish with fresh lemon slices or lemon zest before serving if desired. Cut into squares and serve chilled.