1. Prepare the Crust:  

1. Preheat your oven to 350°F (175°C).

2. In a medium bowl, mix graham cracker crumbs, sugar, and melted butter until combined.

3. Press the mixture firmly into the bottom and sides of a 9-inch pie pan.

4. Bake for 8-10 minutes or until the crust is lightly golden. Set aside to cool.

2. Make the Filling: 

1. In a mixing bowl, whisk egg yolks until slightly thickened.

2. Add sweetened condensed milk, lemon juice, and lemon zest. Mix until smooth and creamy.

3. Pour the filling into the prepared crust and spread it evenly.

3. Bake the Pie:  

1. Bake the pie in the preheated oven for 15-18 minutes, or until the filling is set but slightly jiggly in the center.

2. Remove the pie from the oven and let it cool at room temperature. Then refrigerate for at least 4 hours or until fully chilled.

4. Prepare the Topping (Optional):  

1. In a chilled mixing bowl, whip heavy cream, powdered sugar, and vanilla extract until soft peaks form.

2. Spoon or pipe the whipped cream over the chilled pie for decoration.

5. Serve:  

Garnish with additional lemon zest or thin lemon slices before serving. Enjoy your delicious recipe for lemon pie!