PREHEAT oven to 375° F.
PLACE nuts and powdered sugar in food processor container; cover. Process until nuts are finely ground into a powder, about 30 seconds. Add flour and salt; pulse until combined. Add butter; pulse until the mixture resembles coarse cornmeal with a few pea-sized chunks of butter. With the machine running, add the yolk. Pulse just until the mixture begins to clump together. If the dough is dry, add cold water, 1 teaspoon at a time, and pulse until moistened.) Gather up the dough. Press the dough firmly and evenly onto the bottom and sides of ungreased 9 1/4-inch round tart pan with removable bottom. Freeze for 15 minutes. Place on baking sheet.
COMBINE pumpkin, cream, granulated sugar, brown sugar, egg yolks, pumpkin pie spice and ground ginger in medium bowl. Whisk well to dissolve the sugars. Pour into chilled crust.
BAKE for 10 minutes. Reduce heat to 325° F.; bake for about 50 minutes or until filling is evenly puffed (the center may seem slightly uncooked). Cool completely in pan on wire rack. Remove side of tart pan (place pan on a large can and let the side drop down like a ring around the can.).
SERVE at room temperature (or cover loosely with plastic wrap and refrigerate until well chilled) with dollops of whipped cream and crystallized ginger.
* NOTE: 1/2 teaspoon ground cinnamon, 1/4 teaspoon ground allspice, 1/4 teaspoon freshly grated nutmeg and 1/8 teaspoon ground cloves can be substituted for the pumpkin pie spice.