Mash at 155°F (68°C) for 60 minutes. Boil 90 minutes, following the schedule for adding adjuncts, hops, and spices.
Prepare the pumpkin a few days in advance of the brew day. Using a large knife, halve the pumpkin, remove the seeds, and cut the halves into pieces about 6 inches (15 cm) long. Cover some cookie sheets with aluminum foil, arrange the pumpkin pieces on the cookie sheets, and sprinkle them liberally with brown sugar. Roast in the oven at 375°F (190°C) until soft. This usually takes two to three hours. During roasting, the brown sugar will melt and caramelize onto the pumpkin, providing extra flavor. Remove the pumpkin from the oven and let cool. Then peel off the pumpkin skin, dice the flesh into large cubes (being sure to save the juice for its color and flavor), and store in a covered bowl in the fridge. On brew day, let the pumpkin warm to room temperature and put it in the kettle for the duration of the boil. To avoid a mess in the kettle and clogged valves or siphons, put the pumpkin into either a large fine-mesh bag.
90 minutes: 8 oz dark brown sugar
90 minutes: 5 lb pumpkin (see preparation above)
60 minutes: 0.55 oz Northern Brewer hops (pellet)
5 minutes: 10 tsp ground Saigon cinnamon
5 minutes: 2 tsp fresh ground nutmeg
5 minutes: 2 tsp fresh ground ginger (or 2 tsp dry)
Fermenter: 3 tsp vanilla extract in each fermenter