
In a medium saucepan, whisk together the eggs and sugar until combined. Add in lemon juice, zest, and salt. Heat over medium heat, whisking constantly for 2-3 minutes.

Add in the butter and continue to whisk until melted. Keep whisking until the mixture thickens and coats the back of a spoon.

Remove from heat and transfer to a bowl. Cover with plastic wrap, pressing it down so it touches the top of the curd to prevent a film from forming. Chill for 3 hours or overnight before using. Leftovers can be refrigerated for up to 2 weeks or frozen for up to 3 months.
Crust:

Preheat the oven to 325°F. Spray a 10-inch springform pan lightly with cooking spray.

Mix graham cracker crumbs, sugar, and melted butter together until it resembles damp sand.

Pour the crumb mixture into the prepared springform pan and press evenly into the pan. Use the bottom of a flat glass or measuring cup to press it in well and create an even crust.

Bake for 10 minutes. Allow to cool completely. Keep the oven on for the cheesecake.
Cheesecake Filling:

Add the sugar and lemon zest to a small bowl. Use a fork to combine the sugar and zest, releasing the oils from the zest into the sugar to make lemon sugar.

Add the softened cream cheese to the mixing bowl of a stand mixer and beat with a paddle on medium/high speed for about 1 minute. Scrape down the sides and bottom of the bowl and beat for a few seconds more.

Add the lemon juice, lemon sugar, and sour cream and mix on medium/low speed until just combined. Scrape the bowl again and mix for 30 seconds.

Add the eggs one at a time, beating on low speed until combined, about 30 seconds-1 minute. Scrape the bowl again.