Creamy lemon pie Keto

Ingredients

1 recipe press-in pie crust baked
1 cup heavy cream
4 large egg yolks
1/3 cup freshly squeezed lemon juice
1 tbsp lemon zest
1/4 cup butter chilled and cut into pieces
1 tsp lemon extract
1 tablespoon gelatin 
1/2 to 3/4 cup powdered Swerve Sweetener
1 cup full fat sour cream

Steps

In a large saucepan over medium heat, combine cream, egg yolks, lemon juice, and lemon zest. Cook, whisking frequently, until mixture thickens, about 5 to 8 minutes (but watch carefully, you do not want it to curdle).
Remove from heat and add butter and lemon extract. Sprinkle with gelatin and whisk quickly to combine. Stir in sweetener to taste (I like mine rather tart).
Whisk in sour cream until no lumps remain. Pour into pie shell and refrigerate for at least 4 hours to set - the longer, the better, so overnight is best if you can wait that long. (It's also awesome if you pop it in the freezer for an hour after being refrigerated).
Top with lightly sweetened whipped cream.