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