In a mixing bowl, combine almond flour, coconut flour, granulated erythritol, and salt. Add melted butter and mix until the mixture forms a dough. Press the dough evenly into a 9-inch pie pan, creating a smooth base and rim. Pre-bake the crust at 350°F (175°C) for 10 minutes, then set aside to cool.
In a separate bowl, whisk together pumpkin puree, heavy cream, and powdered erythritol. Add eggs one by one, ensuring each is fully mixed before adding the next. Then, mix in pumpkin pie spice, vanilla extract, and apple cider vinegar. Stir until everything is well incorporated and the mixture is smooth.
Pour the pumpkin filling into the cooled crust, spreading it evenly. Bake in the preheated oven at 350°F (175°C) for 50–60 minutes, or until the filling is set but still slightly jiggly in the center. Let the pie cool completely at room temperature, and then refrigerate for at least 2 hours before serving.
Notes
Store leftovers in the refrigerator covered tightly with plastic wrap or in an airtight container for up to five days. For longer storage, consider freezing individual slices.