In a large bowl, whisk together the sweetened condensed milk, lemon juice, and lemon zest until smooth and slightly thickened.
Gently fold in the whipped topping until fully combined.
Spoon the filling into the graham cracker crust and smooth the top.
Refrigerate for at least 2 hours (or overnight) until firm.
Garnish with whipped cream, lemon slices, and a sprinkle of fresh zest before serving.
Gal Pal Tips
For an extra burst of citrus, add ½ teaspoon pure lemon extract.
Freeze the pie for about 1 hour before serving for a cool, creamy texture on hot summer days.
This pie can be made up to 2 days ahead, making it perfect for entertaining.