Prepare pumpkin puree (See *Notes) or use canned :-(
*For the roasted pumpkin purée:
Preheat oven to 375 degrees F.
Place the whole pumpkin on a baking sheet lined with aluminum foil and roast for 15 minutes.
Remove from oven and carefully slice off the stem and cut the pumpkin into quarters.
Return the pieces to the oven and roast for another 40 minutes or until you can easily run a fork through the flesh and skin of the pumpkin.
Remove the pumpkin pieces from the oven and let cool completely. Scrape out the stringy flesh and seeds and set aside.
Use a spoon to scoop out the flesh and transfer to a food processor. Discard or compost the outer skins.
Purée the pumpkin flesh in the processor until smooth.