Heat the oven to 400°F (200°C). Line a rimmed sheet pan with parchment paper so the pumpkin sugars don't stick and burn.

Cut off the stem, then halve the pumpkin from top to bottom with a large chef's knife. Slice a thin piece off one side first if it rolls.

Scrape out the seeds and stringy pulp with a metal spoon or ice cream scoop. Save the seeds for roasting if you like.

Brush the cut sides lightly with oil if using. Place the halves cut side down on the pan.

Roast 45 to 60 minutes, until the skin looks blistered and slumped and a fork slides into the thickest part with no pressure.

Let the pumpkin cool on the pan for about 15 minutes, until safe to handle. Scoop the soft flesh away from the skin with a spoon.

Blend the flesh in a food processor for about 2 minutes, scraping the bowl once, until completely smooth. Add water 1 tablespoon at a time only if it won't move.

For pie or bread, drain the puree in a coffee-filter-lined strainer set over a bowl in the fridge for 1 to 2 hours, until it holds a soft mound like canned pumpkin.

Use right away, refrigerate in a covered container up to 3 to 4 days, or freeze in 1 3/4 cup (425 g) portions for up to 6 months.