Step 1: Prepare the Crust. In a medium bowl, combine the graham cracker crumbs, melted unsalted butter, and granulated sugar. Mix well until the crumbs are evenly moistened.
Step 2: Form the Crust. Press the crumb mixture firmly into the bottom and slightly up the sides of a 9-inch pie dish. Use the back of a spoon or your fingers to create an even, compact layer. Place the crust in the refrigerator to chill for at least 15 minutes.
Step 3: Whip the Cream Cheese. In a large mixing bowl, beat the softened cream cheese with an electric mixer until it's completely smooth and free of any lumps.
Step 4: Sweeten the Cream Cheese. Gradually add the powdered sugar to the cream cheese, continuing to beat until fully incorporated and the mixture is light and fluffy.
Step 5: Infuse with Lemon. Pour in the fresh lemon juice and stir in the lemon zest. Mix until the filling is silky smooth and beautifully lemony.
Step 6: Fold in Whipped Topping. Gently fold the thawed whipped topping into the lemon-cream cheese mixture using a spatula. Be careful not to overmix; aim for a light, airy consistency with no streaks of white.
Step 7: Fill and Chill. Spoon the luscious lemon filling into the chilled graham cracker crust, spreading it evenly with a spatula to create a smooth top. Cover the pie loosely with plastic wrap.
Step 8: Set and Serve. Refrigerate the pie for a minimum of 4 hours, or ideally, overnight, until it is completely firm. Once set, slice and garnish each piece with a thin lemon slice and a fresh mint leaf before serving.