Although canned pumpkin is prized for convenience, you might discover that the satisfaction of preparing your own pureed pumpkin is worth the effort. Though baking time and water content vary with pumpkin size and variety, any pumpkin can be seeded, baked and pureed for use in recipes calling for canned pumpkin. One pound of raw, untrimmed pumpkin yields about 1 cup of pureed pumpkin. When a recipe calls for a 15 oz. can of pumpkin, use 1-3/4 cups of puree; a 29 oz. can contains 3-1/2 cups.
Preheat oven to 350 degrees F. Cut a clean pumpkin (sugar pumpkins are recommended, I used the one my daughter painted at daycare - washed, of course) in half from stem end to the bottom. Scrape insides with a metal spoon to remove seeds and fibers, reserving seeds, if desired. Place halves, cut sides down, in a roasting pan. Add 1 cup of water. Bake for 60 to 75 minutes or until flesh is tender when pierced with a fork. [Note: I don't have a roasting pan large enough so I put each half in a 9x13 pan.]
When cool enough to handle, scoop out pumpkin flesh with a spoon, draining off any excess liquid and avoiding browned portions. Puree in blender or food processor or mash with potato masher until smooth. Place puree in a cheesecloth-lined sieve set over a deep bowl. Bring ends of cheesecloth over puree to cover. Place a 1 lb. can on top as a weight. Allow to drain about 1 hour or until puree is the consistency of solid pack canned pumpkin. (Or skip draining step and cook puree over low heat, stirring frequently, until any free water is evaporated.)