In a blender or food processor, blend the vanilla wafer cookies and walnuts into fine crumbs.
Transfer to a 9 inch pie pan.
Mix in the butter and maple syrup. Using a fork, press firmly and evenly onto the bottom and sides of the pie pan to create a crust. Chill 10 minutes in the freezer.
In a large bowl, blend the vanilla ice cream, pumpkin and pumpkin pie spice. Spoon into the pie crust. Smooth top with a spatula. Chill 1 hour in the freezer, or until firm.
Before serving pie, place the heavy cream and granulated sugar in a small bowl.
Mix with an electric mixer on high speed until peaks form. Spoon into a pastry bag with a star tip and pipe around the edge of the pie.
In a small saucepan over low heat, melt shortening and chocolate chips, stirring occasionally, until smooth.
Transfer to a small plastic container and chill in the freezer 30 minutes, or until firm.
Remove chocolate from container. Using a vegetable peeler or cheese slicer, scrape the chocolate to form small curls. Use the curls to decorate the pie
