Preheat oven to 350 degrees. Put peanuts and sugar in food processor and pulse until ground up. Pulse in the melted butter. Press evenly into the bottom of a 9-inch spring form pan. Make sure you even it out. Bake 15 minutes. It will start to brown and be pretty set. It will still be a little soft when it comes out of the oven, don’t worry it will firm up. Set aside to cool slightly.
While crust cools, melt chocolate and cream together in microwave, stirring every 30 seconds until smooth and glossy, about 1-2 minutes. Or melt in a bowl over barely simmering water, stirring often until melted and glossy. Spread over crust and put in the freezer for about 30 minutes while making the filling.
Whisk the milk, half and half, eggs, powdered sugar, cornstarch and salt in a medium saucepan. Cook over medium heat, whisking constantly until it becomes the consistency of pudding, 5-6 minutes. Take off the heat and whisk in the cream cheese, peanut butter and the vanilla. Let cool slightly. Spread evenly over the chocolate and refrigerate 4 hours or until cold. Can be made to this point a day ahead.
Run a knife around the edges of the springform pan but do not loosen the outer ring. Whip the cream with the powdered sugar and spread over the cold pie. It is best to chill the pie after spreading the cream for about 30 minutes but not necessary. Remove the outer ring of the springform pan and put on a serving platter. Grate some chocolate over the top for a pretty presentation.