Method

• 01
  Arrange a rack in the lower-middle position of the oven and heat to 350°F. Take the blocks of cream cheese out of their boxes and let them come to room temperature on the counter while you prepare the crust, about 30 minutes.
• 02
  Use your fingers to coat a small pat of butter all over the bottom and sides of a 9-inch or 10-inch springform pan. Cut 2 large pieces of foil and place them on your work surface on top of each other in a cross.
• 03
  Set the springform pan in the middle and fold the edges of the foil up and around the sides of the pan. The foil gives you extra protection against water getting into the pan during the water bath step.
• 04
  Crush the graham crackers in a food processor until they form fine crumbs — you should have 1 1/2 to 2 cups. Melt the butter in the microwave or on the stovetop and mix this into the graham cracker crumbs.
• 05
  The mixture should look like wet sand and hold together in a clump when you press it. If not, add extra tablespoons of water until the mixture holds together. Transfer it into the pan and use the bottom of a glass to press it evenly into the bottom.
• 06
  Place the crust in the oven. Bake until the crust is fragrant and just starting to brown around the edges, 8 to 10 minutes. Let the crust cool on a cooling rack while you prepare the filling.
• 07
  Place the cream cheese, sugar, cornstarch, and salt in the bowl of a stand mixer fitted with a paddle attachment. Mix on medium-low speed until the mixture is creamy, and no lumps of cream cheese remain. Scrape down the beater and the sides of the bowl with a spatula.
• 08
  Add the sour cream, lemon juice, and vanilla and beat on medium-low speed until combined and creamy. With the mixer on medium-low speed, beat in the eggs and the yolk one at a time. Wait until the previous egg is just barely mixed into the batter before adding the next one.
• 09
  Scrape down the beater and sides of the bowl with a spatula. Stir the whole batter a few times by hand, to make sure everything is incorporated. The finished batter should be thick, creamy, and silky. Check to make sure the crust and the sides of the pan are cool.
• 10
  Transfer the pan to a roasting pan or other baking dish big enough to hold it. Bring a few cups of water to a boil and pour the water into the roasting pan, being careful not to splash any water onto the cheesecake. Fill the pan to about an inch.
• 11
  Bake the cheesecake for 50 to 60 minutes. Cakes baked in a 10-inch pan will usually cook in 50 to 55 minutes. The cheesecake is done when the outer two to three inches look slightly puffed and set, but the inner circle still jiggles when you gently shake the pan.
• 12
  Leave the cheesecake in the oven. Turn off the oven and crack the door open. Let the cheesecake cool slowly for 1 hour. Remove the cheesecake from the oven and the water bath, unwrap the foil, and transfer it to a cooling rack.
• 13
  Run a thin-bladed knife around the edge of the cake to make sure it's not sticking to the sides (which can cause cracks as it cools). Let the cheesecake cool completely on the rack.
• 14
  Chill the cheesecake, uncovered, for at least 4 hours or up to 3 days in the refrigerator. This step is crucial for letting the cheesecake set and achieving perfect cheesecake texture — don't rush it.
• 15
  Top the cheesecake and serve.