Preheat the oven to 325°F. Line the bottom of a 9-inch springform pan with parchment paper and place a baking dish filled with 1 inch of hot water on the lowest oven rack.
Mix the almond flour, sweetener, melted butter and salt until it looks like wet sand. Press firmly into the bottom of the pan and bake for 10 minutes, then let it cool while you make the filling.
Blend the cottage cheese in a blender or food processor for 1 to 2 minutes until completely smooth with no curds left. This step is the secret to a silky, classic cheesecake texture.
Beat the softened cream cheese and powdered sweetener on low speed until smooth. Add the blended cottage cheese, lemon juice, vanilla and salt and mix on low until combined.
Add the eggs one at a time, mixing on low just until each one disappears. Do not overmix, as too much air causes cracks.
Pour the filling over the crust and smooth the top. Bake on the middle rack for 55 to 65 minutes, until the edges are set and the center still jiggles slightly like gelatin.
Turn off the oven, crack the door open and let the cheesecake cool inside for 1 hour.Then run a thin spatula around the edge, cool to room temperature and refrigerate for at least 6 hours or overnight before slicing.