Preheat your oven to 325°F. Spray a 9-inch springform cake pan with cooking spray, and line the outside bottom with tin foil to prevent water from getting into the bottom of the pan.
In a medium bowl, combine the graham cracker crumbs and granulated sugar.
Add the melted unsalted butter to the crumb mixture and mix until well combined.
Press the mixture into the bottom of a 9-inch springform pan, with the bottom of a flat cup or your hand creating an even layer. Go halfway up the sides.
Bake the crust in the preheated oven for 14 minutes. Remove from the oven and let it cool while you prepare the raspberry sauce.
Cheesecake Filling:
Preheat or lower your oven to 325°F. Pour water into a sheet pan or roasting pan, filling up only a little less than halfway of the pan. Set aside.
In a large mixing bowl, using a handheld electric mixer, or in a bowl of a stand mixer fitted with the paddle attachment, beat the room temperature cream cheese on medium speed until smooth and creamy.
While the mixer is on low, gradually add the granulated sugar to the cream cheese, continuing to beat until the mixture is well combined and smooth.
With the mixer on low speed, add the room temperature egg yolk and whole eggs all at once and mix just until incorporated. With a rubber spatula, scrape the bottom and the sides of the bowl.
With a rubber spatula, gently fold in ¾ teaspoon salt, lemon extract, poppy seeds, and the corn starch. Fold the entire cheesecake filling until it is smooth, with no lumps remaining. Ensure you get the bottom and the sides. Be careful not to overmix, as this can introduce excess air bubbles into the batter.
Carefully pour the cheesecake filling into the baked graham cracker crust. With the back of the spoon, evenly spread the cheesecake across the top.
Place the cheesecake in the prepped water bath.
Bake in the oven for 50-55 minutes, bake until the middle is barely set and slightly jiggled. If the cake is still jiggling, bake for 5 more minutes. You don’t want any browning on the top
Lemon Curd:
In a medium saucepan, whisk the sugar, lemon zest, and lemon juice. in a small bowl, whisk in the whole eggs and yolks until combined, and then whisk them into the lemon mixture.
Whisking constantly, start cooking the mixture over medium-low heat until it’s thick like pudding, about 6 to 8 minutes. It will start to bubble, keep whisking and cook for about 30 more seconds Remove from the heat and whisk in the butter until fully incorporated.
Strain the mixture through a fine-mesh sieve into a small bowl, pushing it through with a rubber spatula. Press plastic wrap directly onto the surface to prevent a skin from forming. Let it come to room temperature and then refrigerate.
Assembly:
Once the cheesecake has cooled, remove it from the springform pan.
When both elements are cold, start assembly by evenly spreading the lemon curd on top of the cheesecake.
Optional: Add a dollop of whipped cream and sprinkle with poppy seeds for a garnished look. (To make the whipped cream, with a hand mixer or the whisk attachment, whip the heavy cream until medium peak)
Refrigerate the assembled cheesecake for at least an hour before serving, or serve immediately if desired.