01 - Preheat oven to 325°F. Grease a 9-inch springform pan and line the base with parchment paper.
02 - Combine graham cracker crumbs, melted butter, sugar, and salt in a bowl. Press mixture firmly into the bottom of the prepared pan. Bake for 10 minutes, then cool while preparing the filling.
03 - Combine raspberries, sugar, and lemon juice in a small saucepan. Cook over medium heat, stirring constantly, until raspberries break down and mixture thickens, about 5-7 minutes. Push through a fine sieve to remove seeds and set aside to cool.
04 - Beat cream cheese and sugar in a large bowl until smooth and creamy. Add eggs one at a time, mixing well after each addition. Add sour cream, heavy cream, vanilla, lemon juice, and flour. Beat until just combined, being careful not to overmix.
05 - Pour half the cheesecake filling over the crust. Drizzle half the raspberry sauce over the filling and gently swirl with a skewer or knife. Add remaining filling and repeat with remaining raspberry sauce, swirling again to create marble effect.
06 - Place springform pan in a large roasting pan. Fill roasting pan with hot water to reach halfway up the sides of the springform pan to create a water bath.
07 - Bake for 50-60 minutes, until edges are set but center is slightly wobbly. Turn off oven, crack door open, and let cheesecake cool gradually for 1 hour in the oven.
08 - Remove from oven and water bath. Refrigerate at least 4 hours or overnight before unmolding. Serve chilled, optionally topped with extra fresh raspberries or whipped cream.