1. In a mixing bowl, combine the sweetened condensed milk, lemon juice, and lemon zest. Mix until well combined.
2. Gently fold in the whipped cream until the mixture is smooth and evenly blended.
3. Pour the mixture into the graham cracker pie crust, spreading it evenly.
4. Cover the pie with plastic wrap or aluminum foil and freeze for at least 4 hours, or until firm.
5. Once the pie is frozen, remove it from the freezer and let it sit at room temperature for a few minutes before slicing and serving.
6. Garnish with additional lemon zest or whipped cream if desired.
7. Enjoy your refreshing Frozen Lemon Pie!

This recipe captures the simplicity and tangy sweetness of a classic frozen lemon pie, perfect for cooling off on a hot day or serving as a delightful dessert after a meal.