Prepare the Raspberry Sauce:

• In a saucepan, combine raspberries, sugar, lemon juice, and lemon zest.
• Cook over medium heat, stirring occasionally, until the mixture thickens slightly, about 10 minutes.
• Remove from heat and let it cool.

Make the Crust:

• Preheat your oven to 325°F (165°C).
• In a bowl, mix graham cracker crumbs, sugar, and melted butter until well combined.
• Press the mixture firmly into the bottom of a 9-inch springform pan to form an even layer.
• Bake for 10 minutes, then let it cool slightly.

Prepare the Lemon Cheesecake Filling:

• In a large bowl, beat the softened cream cheese until smooth.
• Add sugar and mix until well incorporated.
• Add eggs one at a time, mixing well after each addition.
• Blend in sour cream, heavy cream, lemon zest, and lemon extract until smooth.

Assemble the Cheesecake:

• Pour half of the cheesecake filling over the cooled crust.
• Drizzle half of the raspberry sauce over the filling.
• Pour the remaining cheesecake filling on top.
• Drizzle the remaining raspberry sauce on top and use a knife to gently swirl it into the filling for a marbled effect.

Bake the Cheesecake:

• Place the springform pan on a baking sheet and bake in the preheated oven for 60-70 minutes, or until the center is set but still slightly jiggly.
• Turn off the oven, crack the door open, and let the cheesecake cool in the oven for 1 hour.
• Remove from the oven and refrigerate for at least 6 hours or overnight.

Prepare the Whipped Cream Topping:

• In a chilled bowl, whip the heavy cream until soft peaks form.
• Add powdered sugar and vanilla, then continue whipping until stiff peaks form.

Serve:

• Remove the cheesecake from the springform pan and transfer to a serving plate.
• Pipe or spread the whipped cream on top.
• Garnish with fresh raspberries and lemon zest, if desired.