In a large bowl, blend the cream cheese, sugar, flour, and pumpkin-pie spice with an electric mixer on low speed (at low speed, less air will get into the batter and the cheesecake will be less likely to crack while baking). Add the pumpkin and eggs and beat until well combined. Stir in the white chocolate. Pour the filling into the crust-lined pan, then sprinkle on the chopped hazelnuts.
Bake at 300 degrees for 1 hour. Then turn off the heat and leave the cheesecake in the oven with the door closed for another 30 minutes or longer until set. Remove the cheesecake from the oven and chill. Makes one 9-inch cheesecake.