Preheat the oven to 350° F.
Combine the melted butter, almond flour, sweetener and cocoa powder in a medium sized bowl and mix well.
Transfer the crust dough to a 9-inch pie plate.
Press the crust firmly into the bottom and up the sides.
Bake the crust for 10 minutes.
Remove from the oven and set aside to cool.
Combine the mascarpone and peanut butter and stir gently by hand until creamy and fully combined.
Combine the heavy whipping cream, vanilla, xanthan gum, and erythritol in a large bowl and whip until stiff peaks form.
Carefully fold the peanut butter mixture into the whipped cream.
Transfer the filling to the cooled crust and smooth with a spatula.
Freeze for 30 minutes.
Combine the peanut butter, heavy whipping cream and erythritol in a small bowl and mix well.
Spoon into a plastic baggie and snip the tip off one corner.
Squeeze lines of the peanut butter mixture onto the top of the pie.
Heat the chocolate in a microwave safe bowl until melted.
Transfer the chocolate into a plastic baggie and snip the tip off of one corner.
Drizzle the melted chocolate over the top of the pie.
Sprinkle the top of the pie with chopped peanuts.
