Preheat the oven to 350°F or 175°C. Line an 8-inch square pan with parchment paper.
Mix the almond flour, 1/4 cup sweetener, salt, and melted butter until moist crumbs form.
Press the crust firmly into the pan and bake for 10 minutes. Remove it from the oven and let it cool slightly.
Beat the cream cheese and remaining sweetener until smooth. Add the eggs, lemon juice, zest, vanilla, and salt.
Pour the filling over the crust and bake for 22 to 25 minutes, until the center is nearly set.
Cool completely, then refrigerate for at least 2 hours before slicing into bars.