To make gingersnap crumbs, whirl gingersnaps in a food processor until crumbly.
Homemade Pumpkin Purée:
Preheat oven to 400F. Cut each pumpkin into quarters. Scoop out and discard seeds. Roast pieces in a large baking dish, covered with foil, in centre of preheated oven until fork-tender, about 1 hour. Remove from oven. When cool enough to handle, scoop flesh from skins. Whirl in a food processor until very smooth.