Mix the Filling: In a large bowl, combine the sweetened condensed milk and freshly squeezed lemon juice. Stir well until thoroughly blended.
Fold in Whipped Topping: Gently fold in the whipped topping until it’s evenly mixed with the condensed milk and lemon juice. This will create a light and airy filling.
Assemble the Pie: Pour the lemon mixture into the pre-made graham cracker crust. Spread it out evenly, making sure the filling reaches all edges.
Chill the Pie: Cover the pie with plastic wrap and place it in the refrigerator for at least 4 hours or until it’s set.
Serve and Enjoy: Once set, garnish with lemon zest and slices if desired, slice into wedges, and serve up those happy smiles!