Preheat your oven to 325°F (163°C). Prepare a 9-inch springform pan by greasing it lightly with butter and lining the bottom with parchment paper.

In a mixing bowl, combine the almond flour, ⅓ cup erythritol or monk fruit sweetener, melted butter, 1 tsp vanilla extract, and salt. Stir until the mixture resembles wet sand.

Press the crust mixture evenly into the bottom of the prepared springform pan. Bake for 10-12 minutes until lightly golden. Remove from the oven and let it cool while you prepare the filling.

In a large bowl, beat the softened cream cheese and ¾ cup erythritol or monk fruit sweetener with an electric mixer until smooth and creamy, about 3-4 minutes.

Add the sour cream, remaining 1 tsp vanilla extract, heavy cream, lemon juice, and whey protein powder to the cream cheese mixture. Continue to beat until everything is well combined and fluffy, about another 2-3 minutes.

Pour the cheesecake filling over the cooled crust in the springform pan, smoothing it out with a spatula.

Bake the cheesecake in the preheated oven for 45-50 minutes, or until the edges are set but the center still has a slight jiggle.

Turn off the oven and crack the door, allowing the cheesecake to cool slowly for about an hour. This helps prevent cracking.

Once cooled, refrigerate the cheesecake for at least 4 hours or overnight for the best flavor and texture.

Before serving, you can top the cheesecake with fresh berries, a drizzle of sugar-free chocolate sauce, or a dollop of whipped cream.