Preheat oven to 325°F (165°C). Wrap the outside of a 9-inch springform pan with foil to prevent any leaking. Grease the inside lightly.
In a bowl, stir together the almond flour, melted butter, erythritol, and salt until evenly moistened. Press the mixture firmly into the bottom of the prepared pan in an even layer.
Bake the crust for 10 minutes until lightly golden. Remove and let it cool slightly while you make the filling.
In a large bowl, beat the cream cheese with an electric mixer on medium speed until completely smooth and fluffy, about 3 minutes. Scrape down the sides frequently. Add the erythritol and beat until combined.
Add the peanut butter and beat until fully incorporated. Add the eggs one at a time, mixing on low speed after each just until the yolk disappears. Do not overmix once the eggs are added.
Mix in the sour cream and vanilla extract on low speed until just combined. The batter should be silky smooth.
Pour the filling over the baked crust and smooth the top with a spatula. Tap the pan gently on the counter a few times to release air bubbles.
Bake for 50 to 60 minutes, until the edges are set but the center still has a slight jiggle when you gently shake the pan. Turn the oven off, crack the door open, and let the cheesecake cool inside the oven for 1 hour.
Remove from the oven and refrigerate for at least 6 hours or overnight before releasing the springform ring and slicing.
