Preheat the Oven:

• Preheat your oven to 325°F (160°C). This ensures even baking and prevents burning, creating a consistent texture.
• Line a 9×9-inch (23×23 cm) baking pan with parchment paper, leaving an overhang for easy removal. This prevents sticking and makes cleanup easier, ensuring a smooth baking process.

Prepare the Crust:

• In a medium bowl, combine the graham cracker crumbs, sugar, and melted butter.
• Mix until the crumbs are evenly coated. This ensures a cohesive and flavorful crust, creating a consistent texture.   
   
• Press the mixture firmly into the bottom of the prepared baking pan to form an even crust. Use the back of a spoon or a flat-bottomed glass to help. This creates a compact and sturdy base, ensuring a stable foundation.
• Bake for 8–10 minutes, then remove from the oven and allow to cool slightly. This sets the crust and prevents it from becoming soggy, ensuring a crisp texture.

Make the Cheesecake Filling:

• In a large bowl, beat the softened cream cheese and sugar with an electric mixer on medium speed until smooth and creamy. This ensures a lump-free, well-combined filling, creating a consistent texture.
• Add the eggs, one at a time, mixing well after each addition. This ensures even incorporation and prevents overmixing, ensuring a smooth filling.
• Stir in the vanilla extract and sour cream until fully incorporated. Avoid overmixing, as it can make the filling tough. This ensures a smooth and creamy texture, preventing a dense filling.

Assemble the Cheesecake Bars:

• Pour the cheesecake batter evenly over the cooled crust and smooth the top with a spatula. This creates a smooth and even base for the swirls, ensuring a consistent texture.
• Spoon small dollops of the lemon curd on top of the cheesecake layer, spacing them out evenly. This creates a visually appealing pattern, enhancing the presentation.
• Use a toothpick or a skewer to gently swirl the lemon curd into the cheesecake batter, creating a marbled effect. Be careful not to over-swirl. This ensures a beautiful marbled design, enhancing the visual appeal.

Bake:

• Bake in the preheated oven for 30–35 minutes, or until the edges are set and the center is slightly jiggly. This ensures the cheesecake is cooked through but not overbaked, creating a perfect texture.
• Remove from the oven and allow to cool to room temperature in the pan. This prevents cracking and allows the cheesecake to set, ensuring a smooth and consistent texture.

Chill:

• Once cooled, refrigerate the cheesecake bars for at least 2 hours (or overnight) to set completely. This ensures a firm and sliceable texture, creating a perfect consistency.

Slice and Serve:

• Lift the cheesecake bars out of the pan using the parchment paper overhang. This makes removal easy and prevents damage to the bars, ensuring a clean presentation.
• Slice into squares or rectangles and garnish with a dusting of powdered sugar, lemon zest, or a dollop of whipped cream, if desired. This adds a finishing touch and enhances the presentation, creating an elegant dessert.