1. Following the instructions in Perfect Piecrust 101, line a 9-inch pie pan with the pie dough and flute the edges. Line the pastry shell with aluminum foil. Freeze for 20 minutes.
2. Position a rack in the lower third of the oven and place a baking sheet on the rack. Preheat the oven to 400°F.
3. Fill the foil with pie weights or dried beans. Place the pastry shell on a baking sheet. Bake until the edges of the crust look set, about 12 minutes. Remove from the oven and lift off the foil and beans.
4. Meanwhile, prepare the filling. Process the hazelnuts, brown sugar, and granulated sugar in a food processor with the metal chopping blade until the hazelnuts are powdery. Transfer to a medium bowl and add the pumpkin, half-and-half, eggs, cinnamon, ginger, cloves, and nutmeg. Whisk well.
5. Pour the filling into the hot crust and return to the oven. Bake for 15 minutes. Reduce the oven temperature to 350°F. Bake until the filling is puffed with a 1-inch diameter area in the center that remains unpuffed, about 45 minutes.
6. Transfer to a wire rack and cool completely. Cover the pie and refrigerate until chilled. (The pie can be prepared 1 day ahead.)
7. To prepare the topping, whip the heavy cream, confectioners’ sugar, and vanilla until soft peaks form. Transfer the cream to a pastry bag fitted with a ½-inch fluted tip. Pipe 8 large rosettes around the edge of the pie. (Or spread the cream over the filling in a thin layer.) Serve chilled.