Preheat the oven to 325°F (160°C).

In a bowl, combine the graham cracker crumbs, melted butter, and sugar. Mix until it resembles wet sand, then press firmly into the bottom of a greased 9x13 inch baking dish.

Bake the crust for 10 minutes and let cool.

In a large mixing bowl, beat the softened cream cheese until smooth. Gradually add sugar, mixing well. Then, add eggs one at a time, blending after each addition.

Stir in the vanilla extract, sour cream, lemon zest, and lemon juice until well combined and creamy.

Pour half of the cheesecake filling over the cooled crust. In a separate bowl, mix half of the remaining cheesecake filling with a tablespoon of lemon juice and pour over the first layer.

Pour the rest of the plain cheesecake filling on top and swirl the layers together using a knife.

Bake in the preheated oven for 35-40 minutes, or until the center is slightly jiggly but not liquid, and the edges should be set.

Turn off the oven and let the bars cool in the oven with the door slightly open for about an hour.

After cooling, refrigerate for at least 4 hours, preferably overnight, to let flavors meld and the texture firm up.

Slice into squares and enjoy this lemony delight with fresh berries, whipped cream, or mint leaves!