Prep your pan and oven. Preheat the oven to 325°F (163°C).
Line the bottom of a 9-inch springform pan with parchment and lightly grease the sides. Wrap the outside of the pan with a double layer of foil if you plan to use a water bath.
Make the crust. In a bowl, mix almond flour, powdered sweetener, and salt. Stir in melted butter and vanilla until the mixture resembles damp sand.
Press evenly into the prepared pan, going slightly up the sides.
Par-bake the crust. Bake for 10 minutes until lightly golden. Set aside to cool while you make the filling.
Beat the cream cheese. In a large bowl, beat the cream cheese on medium speed until smooth and fluffy, about 1–2 minutes. Scrape down the bowl to avoid lumps.
Add peanut butter and sweetener. Beat in the peanut butter and granulated sweetener until fully combined and smooth.
Scrape the bowl well, especially at the bottom.
Blend in sour cream, vanilla, and salt. Mix just until smooth. Avoid overmixing to minimize air bubbles.
Add the eggs. Beat in eggs one at a time on low speed, just until incorporated. Stop mixing as soon as the batter is uniform.
Pour and smooth. Pour the filling over the cooled crust.
Tap the pan gently on the counter to release any air bubbles. For the smoothest top, run a spatula in a circle to even it out.
Bake with or without a water bath. For the most even bake and fewer cracks, place the springform pan in a larger roasting pan and pour hot water around it, halfway up the sides. Bake at 325°F for 55–70 minutes, until the edges are set and the center still jiggles slightly.
Cool gradually. Turn off the oven, crack the door, and let the cheesecake sit inside for 45 minutes.
Then remove, take off the water bath, and cool to room temperature.
Chill to set. Cover and refrigerate for at least 6 hours, preferably overnight. This step improves both texture and flavor.
Optional topping. Warm heavy cream to a gentle simmer. Pour over chopped chocolate and rest for 2 minutes, then stir smooth.
Whisk in peanut butter until glossy. Spread over the chilled cheesecake and garnish with crushed peanuts.
Slice and serve. Use a hot, clean knife for neat slices. Wipe between cuts for the best presentation.