01 - Preheat oven to 325°F. Lightly grease a 9-inch springform pan and line bottom with parchment paper.
02 - Combine crushed graham crackers, melted butter, and 2 tbsp sugar in bowl. Press mixture evenly into pan base. Bake 8 minutes, then set aside to cool.
03 - In small saucepan, combine blackberries, 4 tbsp sugar, and lemon juice. Cook over medium heat 8-10 minutes until berries break down and mixture thickens, stirring frequently. Puree with hand blender, strain through fine mesh sieve to remove seeds. Cool completely.
04 - Using mixer, beat cream cheese and 1 cup sugar until smooth and creamy. Add eggs one at a time, mixing well after each addition. Blend in sour cream, vanilla, and flour until just combined.
05 - Pour cheesecake filling over cooled crust. Dollop spoonfuls of blackberry puree over top, then swirl gently with skewer or knife for marbled effect.
06 - Place pan in larger tray filled with hot water to create water bath. Bake 50-60 minutes until center is almost set but slightly wobbly.
07 - Turn off oven, crack door open, let cheesecake cool slowly 1 hour. Remove from oven and refrigerate at least 4 hours or overnight before serving.
08 - Top with fresh blackberries, mint leaves, and whipped cream if desired before serving.