Preheat oven to 300 °F (150 °C).

Wrap a 10″ springform pan with two layers of heavy-duty foil. If using crust, press it firmly into the pan.

In a mixer fitted with paddle attachment, beat cream cheese and butter until smooth.

Add eggs one at a time, mixing just until incorporated.

Mix in sour cream until silky.

Add sugar, cornstarch, scraped vanilla seeds (or extract), and lemon juice, beating ~2 minutes until smooth and lump‑free.

Pour batter into prepared pan and place inside a roasting pan. Carefully pour boiling water into the outer pan until it reaches halfway up the springform sides.

Bake 2 hours, until set but slightly wobbly in the center.

Turn off oven; let cheesecake cool inside for 1 hour with door ajar. Remove from water bath, unwrap, and cool completely at room temperature.

Chill in refrigerator overnight (at least 6 hours) to fully set.

Release springform, slice cleanly, and serve plain or topped with berries, caramel, or whipped cream.