Prep the pan: Heat oven to 325°F (163°C). Wrap the outside of a 9-inch springform pan with two layers of heavy-duty foil to prevent leaks.
Make the crust: Mix graham crumbs, sugar, salt, and melted butter until the texture resembles wet sand.
Press firmly into the bottom and slightly up the sides of the pan.
Par-bake crust: Bake 8–10 minutes until lightly fragrant. Cool while you make the filling. Keep the oven at 325°F.
Soften dairy: Ensure cream cheese, sour cream, heavy cream, and eggs are at room temp.
This is key for a smooth batter.
Beat the cream cheese: In a mixer on medium-low, beat cream cheese until smooth and creamy, 1–2 minutes. Scrape the bowl well.
Add sugar and cornstarch: Mix in sugar, cornstarch, and salt on low until combined and silky. Avoid whipping in excess air.
Add sour cream, cream, and vanilla: Blend on low until just combined.
Scrape the bowl again.
Add eggs: Add eggs and yolk one at a time on low speed, mixing just until incorporated. Stir in lemon zest or juice if using.
Assemble the bath: Pour filling over crust. Place the foil-wrapped pan in a large roasting pan.
Pour hot water into the roasting pan until it reaches halfway up the sides of the springform.
Bake: Bake 55–70 minutes. The edges should be set, with a 2–3 inch jiggly center. Do not overbake.
Cool gradually: Turn off oven, crack the door, and let cheesecake rest inside 45 minutes.
Then remove the pan from the water and cool completely on a rack.
Chill: Refrigerate, uncovered, at least 6 hours (preferably overnight). Run a thin knife around the edge, then unmold and slice with a hot, clean knife.