Center the oven rack; preheat oven to 350°F. In a medium bowl, thoroughly mix the ground pretzels, sugar, and butter. Pour the mixture into a 9-inch pie plate, and then press it against the bottom and up the sides of the plate. Bake just until slightly colored -- 8-10 minutes. Cool completely on a wire rack.
In the bowl of a standing mixer, whip the cream to soft peaks. Transfer the cream to a medium bowl, and pop it into the refrigerator. Then add to empty (but not washed-out) mixing bowl the peanut butter and cream cheese. Mix at medium speed until well combined. Add the confectioners' sugar, and mix at low speed. Add half of the previously-whipped cream, and mix at medium speed just until the mixture turns rich and silky.
Pour the peanut butter mixture into the pretzel crust shell, and smooth it out with a spatula. Top with the remaining whipped cream. Garnish with the crushed peanuts and melted chocolate. Refrigerate until set -- at least 1 hour. Alternatively, you can freeze the pie. Frozen pie tastes like peanut butter ice cream!