Ginger Shortbread Crust:
Place flour, sugar and ground ginger in a food processor and pulse a few times to mix together. Add egg yolk and softened butter and pulse until the dough comes together.
Press the dough onto the bottom of a 9-inch springform pan with your fingers, then smooth it out with an offset spatula. Prick the crust a few times with a fork to prevent the crust from puffing up during baking.
Bake for 15 minutes or until the crust is a light golden brown.
Beat the reserved egg white lightly, then brush it onto the crust to prevent it from becoming soggy.
Preheat the oven to 350°F.
Fill a baking pan about 3/4-inch deep with hot water. Place it on the bottom rack of the oven to create a steam bath.
In a large mixing bowl, beat together the cream cheese, sugar, whole eggs and egg yolks until creamy.
Sift together the flour, cinnamon, cloves and ginger, and add to the cream cheese mixture; mix well.
Beat in the heavy cream and vanilla, then add the pumpkin and beat just until mixed thoroughly.
Pour the cream cheese batter over the prepared crust and bake on the middle oven rack for 1 hour and 30 minutes.
Allow the cheesecake to cool completely.
Place in the refrigerator and chill overnight.
Use a jack-o'-lantern template to decorate the cheesecake with the cocoa powder.