Preheat oven to 325°F (165°C). Mix almond flour and melted butter, then press into the bottom of a 9-inch springform pan. Bake 10 minutes, then cool slightly.
Beat twaróg until smooth. Add eggs one at a time, beating well after each addition.
Mix in sweetener, cream, vanilla, lemon zest, and salt until smooth.
Pour filling over the crust.
Bake 50–60 minutes until the center is just set with a slight jiggle.
Turn off the oven and let the cheesecake cool inside with the door cracked for 1 hour.
Chill in the fridge at least 4 hours, ideally overnight, before slicing.