Preheat your oven to 325°F (160°C). Place the oven rack in the center position.

In a food processor or using a plastic bag and rolling pin, crush the graham crackers into fine crumbs.

In a mixing bowl, combine the graham cracker crumbs, granulated sugar, and melted butter. Stir until the crumbs are evenly coated.

Press the mixture firmly into the bottom of a 9-inch springform pan to form the crust. Use the back of a spoon or the bottom of a measuring cup to help pack the crust evenly.

Bake the crust in the preheated oven for 10 minutes. Remove from the oven and set aside to cool slightly.

In a large mixing bowl, beat the softened cream cheese and granulated sugar together with an electric mixer or stand mixer until smooth and creamy, about 2-3 minutes.

Add the flour and beat until well combined.

Add the eggs one at a time, beating well after each addition.

Mix in the sour cream, vanilla extract, and lemon zest (if using) until the filling is smooth and well combined.

Wrap the outside of the springform pan with aluminum foil to prevent water from leaking into the pan during the water bath.

Pour the cheesecake filling over the cooled crust in the springform pan. Use a rubber spatula to smooth the top.

Place the springform pan inside a larger baking pan. Fill the larger baking pan with hot water to create a water bath, ensuring the water comes about halfway up the sides of the springform pan.

Carefully transfer the baking pan with the cheesecake to the preheated oven.

Bake the cheesecake for 60-70 minutes, or until the edges are set but the center is still slightly jiggly.

Turn off the oven and leave the cheesecake inside with the door closed for an additional hour to cool gradually.

Remove the cheesecake from the oven and let it cool completely at room temperature.

Once cooled, refrigerate the cheesecake for at least 4 hours, or preferably overnight, to allow it to set completely.

Before serving, run a knife around the edge of the cheesecake to loosen it from the sides of the springform pan. Carefully remove the sides of the pan.

Slice the cheesecake into wedges and serve chilled.