Pumpkin Prep:
You need to 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. (As an aside, for those who are into sustainable brewing, the boiled pumpkin flesh makes excellent pies.)
To avoid a mess in the kettle and clogged valves or siphons, put the pumpkin into either a large fine-mesh bag designed for fruit or a hop spider equipped with a paint-straining bag.