Step 1: Prepare the Crust

1. Preheat the Oven: Preheat your oven to 325°F (160°C) and line a 9×9 inch baking pan with parchment paper, leaving some overhang on the sides to make it easy to lift out the bars.
2. Mix the Crust Ingredients: In a medium bowl, combine the graham cracker crumbs, granulated sugar, and melted butter. Stir until the mixture resembles wet sand.
3. Press into the Pan: Pour the graham cracker mixture into the prepared pan. Use the back of a spoon or a measuring cup to firmly press it into an even layer, covering the bottom of the pan.
4. Bake the Crust: Bake the crust in the preheated oven for 8-10 minutes, or until it’s lightly golden and fragrant. Remove from the oven and allow it to cool slightly while you prepare the filling.

Step 2: Make the Lemon Cheesecake Filling

1. Beat the Cream Cheese: In a large mixing bowl, beat the softened cream cheese with an electric mixer on medium speed until smooth and creamy, about 2-3 minutes. Make sure to scrape down the sides of the bowl as needed to ensure there are no lumps.
2. Add the Sugar and Sour Cream: Gradually add the granulated sugar and sour cream, mixing until fully incorporated and smooth.
3. Add the Eggs One at a Time: Add the eggs, one at a time, mixing well after each addition to ensure a smooth batter.
4. Incorporate the Lemon Juice and Zest: Add the fresh lemon juice, lemon zest, and vanilla extract to the mixture, stirring until well combined. The lemon juice and zest will add a burst of citrus flavor to the cheesecake layer.
5. Pour over the Crust: Pour the lemon cheesecake mixture over the baked graham cracker crust, smoothing it into an even layer with a spatula.

Step 3: Bake the Cheesecake Bars

1. Bake: Bake the cheesecake bars in the preheated oven for 35-40 minutes, or until the edges are set and the center is slightly jiggly. The residual heat will help set the center as the bars cool.
2. Cool and Chill: Remove the pan from the oven and let it cool to room temperature, about 1 hour. Once cooled, cover and refrigerate the bars for at least 3 hours, or overnight for best results.

Step 4: Slice and Serve

1. Lift and Slice: Use the parchment overhang to carefully lift the cheesecake bars from the pan. Place on a cutting board and use a sharp knife to slice into 16 squares. For clean slices, wipe the knife between each cut.
2. Garnish: Dust with powdered sugar, top with fresh lemon zest, or add a dollop of whipped cream and fresh berries for an elegant touch.
3. Serve: Serve chilled and enjoy the refreshing, creamy lemon flavor!