Step-by-Step Instructions

1. Prepare the Crust:
   • Preheat your oven to 325°F (160°C). Line a 9×13-inch baking pan with parchment paper, allowing the edges to hang over the sides for easy removal.
   • In a medium mixing bowl, combine the graham cracker crumbs, sugar, and melted butter. Stir until the mixture resembles wet sand.
   • Press the mixture firmly into the bottom of the prepared baking pan to form an even layer. Bake for 10 minutes, then set aside to cool slightly.
2. Make the Cheesecake Filling:
   • In a large mixing bowl, use an electric mixer to beat the softened cream cheese until smooth and creamy, about 2-3 minutes.
   • Add the sugar and beat until well combined, scraping down the sides of the bowl as needed.
   • Beat in the eggs one at a time, mixing well after each addition.
   • Add the vanilla extract and sour cream, and mix until smooth and fully incorporated.
3. Create the Lemon Swirl:
   • In a small mixing bowl, combine the lemon juice, lemon zest, sugar, and flour. Mix until smooth and well combined.
   • Pour the cheesecake filling over the cooled crust, spreading it into an even layer.
   • Spoon the lemon mixture over the cheesecake filling in small dollops, then use a toothpick or knife to gently swirl the lemon mixture into the cheesecake, creating a marbled effect.
4. Bake and Cool the Bars:
   • Bake the cheesecake bars in the preheated oven for 40-45 minutes, or until the center is just set and the edges are lightly golden.
   • Turn off the oven and crack the door open slightly, allowing the bars to cool gradually in the oven for about 1 hour. This helps prevent cracks.
   • Once cooled, refrigerate the bars for at least 2 hours or overnight to fully set.
   • Use the parchment paper overhang to lift the cheesecake bars out of the pan. Slice into squares and serve chilled.