Begin by mixing graham cracker crumbs with melted butter in a large bowl until evenly combined. Press the mixture firmly into the bottom of an 8-inch springform pan to create an even layer. Place the pan in the refrigerator for about 30 minutes to allow the crust to firm up nicely before adding the filling.

In a large mixing bowl, beat the cream cheese, sugar, and cornstarch together on medium speed until the mixture is creamy and smooth, which should take about 3–4 minutes. Ensure there are no lumps for the best texture.

Next, gradually add the eggs and extra yolk to the cream cheese mixture, mixing on low speed until just combined. Stop mixing as soon as you see no streaks of egg.

Lower the mixer speed and carefully stir in the sour cream, lemon juice, and vanilla extract. Mix for another minute until the ingredients are well blended.

Once your cheesecake filling is smooth, pour it over the chilled crust in the springform pan. Use a spatula to gently spread the filling evenly, ensuring no air bubbles are trapped.

To prevent cracking during baking, wrap the bottom and sides of the springform pan with aluminum foil to ensure it is watertight. Place the pan in a roasting pan and pour hot water into the roasting pan until it reaches halfway up the sides of the springform pan.

Preheat the oven to 302°F (150°C) and carefully transfer the roasting pan with the cheesecake into the oven. Bake for 30–45 minutes, or until the edges are set but the center jiggles slightly when nudged.

After baking, turn off the oven and crack the oven door open, letting the cheesecake cool slowly for 1 hour.

Finally, place the cooled cheesecake in the refrigerator and let it chill overnight.