Preheat oven to 325°F (160°C). Grease a 9‑inch springform pan and wrap the outside with foil.

In a medium bowl, mix graham cracker crumbs, ¼ cup sugar, and melted butter until well combined. Press firmly into the bottom of the prepared pan to form the crust. Bake for 10 minutes, then set aside.

While crust bakes, melt the white chocolate in a heat‑proof bowl over simmering water or in 20‑second microwave bursts, stirring until smooth; allow to cool slightly.

In a large bowl, beat cream cheese and ¾ cup sugar until smooth and creamy. Add eggs one at a time, blending well after each. Stir in vanilla extract.

Mix in sour cream, then gently fold in the melted white chocolate until evenly incorporated.

Pour half of the cheesecake batter over the prebaked crust.

Spoon half of the strawberry purée (and strawberry jam if using) over the batter. Gently swirl with a knife.

Pour the remaining cheesecake batter on top, then swirl with the remaining purée.

Bake for 50–60 minutes, or until the edges are set and the center jiggles just slightly.

Turn off the oven, crack the door, and let the cheesecake cool inside for 1 hour.

Remove from the oven and refrigerate for at least 4 hours or overnight to fully set.

Before serving, run a knife around the pan edge, remove the springform side, and garnish with sliced fresh strawberries if desired.