Preheat & Prep: Begin by preheating your oven to 325°F (163°C). Line a 9x13 inch baking pan with parchment paper for easy removal later.
Make the Crust: In a medium bowl, combine graham cracker crumbs, 1/4 cup sugar, and melted butter. Mix until well combined, then press this mixture firmly into the bottom of the prepared baking pan to form your crust.
Prepare the Filling: In a large bowl, beat the softened cream cheese and 1 cup of sugar together until smooth. Add the vanilla extract and mix thoroughly. Now, add the eggs one at a time, mixing well after each addition. Then, blend in the sour cream, flour, lemon juice, and lemon zest until you have a smooth mixture.
Add the Raspberry Swirl: Pour the cream cheese mixture over your crust. Dollop the raspberry preserves over the top in spoonfuls, then take a knife and gently swirl the preserves into the filling to create a beautiful marbled effect.
Bake: Bake in your preheated oven for 45-50 minutes or until the center is set and the edges are lightly browned.
Cool & Chill: Let the cheesecake cool to room temperature, then refrigerate for at least 4 hours (or overnight!) before slicing into bars.
Garnish & Serve: Cut into squares and garnish each bar with fresh raspberries, a slice of lemon, and a dollop of whipped cream for that extra touch of elegance!