Preheat the oven to 350°F (175°C). In a mixing bowl, combine almond flour, erythritol, melted butter, and vanilla extract. Mix until well combined.

Press the mixture into the bottom of a 9-inch springform pan to form an even layer. Bake for 10 minutes, then remove from the oven and let cool.

In a large mixing bowl, beat the softened cream cheese and erythritol together until smooth and creamy.

Add the eggs one at a time, mixing well after each addition. Then add sour cream, vanilla extract, and lemon juice (if using). Mix until fully combined.

Pour the filling over the cooled crust in the springform pan. Bake in the preheated oven for 50-60 minutes, or until the center is set and the edges are lightly golden.

Turn off the oven and leave the cheesecake inside for an additional hour to cool gradually.

Remove the cheesecake from the oven and let it cool to room temperature. Then refrigerate for at least 4 hours or overnight before serving.

Slice and enjoy your keto cheesecake!