1. Prepare the Graham Cracker Crust: A Buttery, Crunchy Base

1. Prepare Springform Pan: Line the bottom of an 8-inch (20 cm) springform pan with parchment paper. You can also grease the sides of the pan for extra insurance against sticking.
2. Crush Graham Crackers: Blend the graham crackers in a food processor until they form fine crumbs. You can also crush them in a ziplock bag using a rolling pin.
3. Combine with Butter: In a medium bowl, combine the graham cracker crumbs with the melted butter. Mix well until the crumbs are evenly moistened and resemble wet sand.
4. Press into Pan: Pour the crumb mixture into the prepared springform pan. Use your fingers or the bottom of a measuring cup to press the crumbs firmly and evenly into the bottom of the pan, and slightly up the sides.
5. Chill: Place the pan in the refrigerator while you prepare the cheesecake filling. Chilling the crust helps it firm up and prevents it from becoming soggy.

2. Make the Cheesecake Batter: Creamy, Tangy, and Smooth

1. Boil Water: While the crust is chilling, bring a large pot or kettle of water to a boil. You’ll need this for the water bath later.
2. Beat Cream Cheese: In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl using a handheld mixer), beat the softened cream cheese on medium speed until it’s completely smooth and lump-free, about 2 minutes.
3. Add Sugar and Cornstarch: Add the granulated sugar and cornstarch to the cream cheese. Beat on medium speed until well combined, scraping down the sides of the bowl with a rubber spatula as needed.
4. Incorporate Eggs and Yolk: Add the eggs and egg yolk one at a time, beating on low speed until just combined after each addition. Do not overmix.
   • Tip: Overmixing after adding the eggs can incorporate too much air, which can cause the cheesecake to crack during baking.
5. Add Sour Cream, Vanilla, and Lemon Juice: Add the sour cream, vanilla extract, and lemon juice to the mixture. Beat on low speed until just combined. Scrape down the sides of the bowl to ensure everything is thoroughly mixed.

3. Assemble and Bake: The Water Bath Technique for a Perfectly Smooth Cheesecake

1. Pour Filling: Remove the springform pan with the chilled crust from the refrigerator. Pour the cheesecake batter over the graham cracker crust.
2. Tap to Remove Air Bubbles: Gently tap the springform pan on the counter a few times to release any air bubbles trapped in the batter.
3. Prepare Water Bath:
   • Wrap Pan: Wrap the outside of the springform pan tightly with two layers of aluminum foil, ensuring a secure seal to prevent water from seeping in.
   • Place in Roasting Pan: Place the wrapped springform pan inside a large roasting pan.
   • Add Water: Carefully pour the boiling water into the roasting pan, filling it about halfway up the sides of the springform pan.
4. Bake: Carefully transfer the roasting pan with the cheesecake to the preheated oven (302°F / 150°C). Bake for about 1 hour and 30 minutes.
   • Check for Doneness: The cheesecake is done when the edges are set and lightly golden, but the center still jiggles slightly when the pan is gently shaken.
5. Cool in Oven: Turn off the oven and leave the cheesecake inside with the door slightly ajar for another 30-45 minutes. This gradual cooling process helps prevent the cheesecake from cracking.
6. Cool at Room Temperature: Remove the roasting pan from the oven and carefully remove the cheesecake from the water bath. Let the cheesecake cool completely at room temperature on a wire rack.
7. Chill: Once cooled to room temperature, cover the cheesecake with plastic wrap and refrigerate for at least 6 hours, or preferably overnight. Chilling allows the cheesecake to fully set and the flavors to meld.

4. Serve: Enjoying Your Masterpiece

1. Remove from Pan: Once fully chilled, carefully remove the cheesecake from the springform pan by releasing the latch and lifting off the sides.
2. Serve: Slice the Philadelphia New York Cheesecake into wedges and serve.