Coat the pan with butter/parchment paper. bottom and sides of a 9-inch or 10-inch springform pan.
MAKE CRUST
Prepare the crust. Crush the graham crackers or shortbread in food processor until they form sand like crumbs. Melt the butter in the microwave and drizzle in.
Bake the crust 8 – 10 min. until the crust is fragrant and just starting to brown around the edges. Cool.
MAKE FILLING
Mix the cream cheese, sugar, cornstarch/flour, and salt in stand mixer with paddle attachment. Mix on medium-low speed until the mixture is creamy, like thick frosting, and almost no lumps of cream cheese remain.
Mix in the sour cream, lemon juice, and vanilla.
Mix in the eggs and yolk one at a time. Wait until the previous egg is just barely mixed into the batter before adding the next one.
Stir a few times by hand. Scrape down the beater and sides of the bowl with a spatula. Stir the whole batter a few times by hand, being sure to scrape the bottom of the bowl, to make sure everything is incorporated.
Pour the batter over the cooled crust into an even layer.
Transfer the pan to the water bath or steam oven.
Bake the cheesecake for 50 to 60 minutes. Cakes baked in a 10-inch pan will usually cook in 50 to 55 minutes; cakes in a 9-inch pan will cook in 55 to 60 minutes. The cheesecake is done when the outer two to three inches look slightly puffed and set, but the inner circle still jiggles (like Jell-O) when you gently shake the pan. Some spots of toasted golden color are fine, but if you see any cracks starting to form, move on to the next step right away.
Cool the cheesecake in the oven. Leave the cheesecake in the oven. Turn off the oven and crack the door for about 1 hour then transfer to cooling rack.
Cool completely on the rack.
Chill the cheesecake uncovered in the refrigerator for AT LEAST 4 hours or up to 3 days.
Notes
You can use either graham crackers or shortbread or a combination of both for the crust. My preference is a shortbread crust.