01 - Preheat oven to 325°F. Line an 8-inch square baking pan with parchment paper, leaving an overhang on the sides.
02 - Combine graham cracker crumbs, sugar, and melted butter in a medium bowl. Press firmly into the bottom of the prepared pan. Bake for 8 minutes and allow to cool slightly.
03 - Beat cream cheese and sugar until smooth and creamy. Add eggs one at a time, mixing well after each. Incorporate sour cream, flour, lemon zest, lemon juice, and vanilla extract until just combined.
04 - Pour cheesecake filling over cooled crust and smooth the surface.
05 - Mash raspberries with sugar in a small bowl. Spoon dollops over the cheesecake layer and gently swirl with a toothpick or knife.
06 - Bake for 30 to 32 minutes, until the center is set and edges are lightly golden.
07 - Cool completely at room temperature, then refrigerate for at least 2 hours before slicing. Garnish with extra raspberries and lemon zest if desired.