For the pumpkin:
Preheat the oven to 375 degrees F.
Cut the pumpkin in half. Remove the stem from the pumpkin and scrape out the pulp and seeds. Lay the pieces cut-side down on a baking sheet lined with aluminum foil. Rub vegetable oil all over the skin, pierce with a fork and bake until fork-tender, about 1 hour. Cool.
For the crust:
Reduce the oven to 350 degrees F.
In a food processor crush the gingersnap cookies. Stir in the melted butter until combined. Pour into a 9" pie plate and press firmly on the sides and bottom. I use the bottom of my measuring cup to press the crust.
Bake at 350 degrees for 5 minutes.
For the pumpkin filling:
Scoop out the pulp from the roasted pumpkin and puree in a food processor until smooth.
Add the condensed milk, cream, cornstarch, molasses, oil, cinnamon, ginger, cloves, salt and eggs to the food processor. Pulse combine thoroughly.
Pour the filling into the crust and bake at 350 degrees F until the filling is set in the center, about 1 hour.
Transfer the pie to a rack to cool completely.
Garnish with whip cream if desired.