Start by making the condensed milk. Bring the whipping cream to a boil over medium heat then lower the heat and simmer for 15 minutes to thicken, Try not to let the mix fully boil, just a very low simmer will work.
Remove the heavy cream from the heat and add the powdered erythritol and butter and stir.
Sprinkle the xanthan gum over the heavy cream mix and whisk vigorously to prevent clumping. Set the mix aside to cool.
Preheat your oven to 325 degrees F and get an 8 inch cake pan ready.
Combine the almond flour, granulated erythritol and melted coconut oil together in a medium bowl. Once mixed, pour into the cake pan and press down to make a firm, even crust.
Bake the crust in the preheated oven for about 15 minutes or until it begins to turn golden brown. Set aside to cool.
Beat the cream cheese and lime zest in a large bowl until very smooth (no cream cheese clumps!). Add the egg yolks slowly, incorporating fully after each addition.
Add the condensed milk mix, lime juice and vanilla extract to the cream cheese bowl and mix until smooth.
Pour the filling over the crust and return the pan to the oven, cooking for 18 minutes. The cheesecake will not brown!
Let cool at room temperature for about an hour and them place in the fridge to cool completely. The cheesecake will get firm after about 2 hours.