Preheat oven to 325°F. Line the bottom of a 9-inch springform pan with parchment paper.
Mix crushed graham crackers with melted butter. Press into the bottom of the pan to form the crust. Bake for 10 minutes, then let cool.
In a large bowl, beat cream cheese until smooth. Add sugar and mix until combined.
Add eggs one at a time, mixing well after each addition.
Mix in sour cream, lemon zest, lemon juice, and vanilla until smooth.
Pour the cheesecake filling over the crust.
In a small bowl, stir raspberry jam with water until smooth. Drop spoonfuls over the filling and swirl with a knife.
Bake for 55-60 minutes or until edges are set and the center slightly jiggles.
Turn off the oven, crack the door open, and let the cheesecake cool inside for 1 hour.
Refrigerate for at least 4 hours or overnight before serving.
Top with fresh raspberries and whipped cream if desired.