Preheat oven to 375 degrees. Line a baking sheet with parchment paper. Cut pumpkin in half and remove seeds by combing through the fibrous strings with your fingers.
Scrape out and discard fibrous strings. If you want to save and roast the pumpkin seeds, rinse them in cold water and dry on a kitchen towel.
Cut pumpkin into quarters (5 or 6 inches wide each). Place pieces skin-side down on prepared baking sheet and roast uncovered until tender, about 1 to 1-1/2 hours.
Remove from oven and cool completely. Scrape pumpkin pulp off skin, discarding the skin.
Add the pulp to a blender or food processor and blend until smooth. Place pumpkin puree into a cheesecloth-lined sieve, and allow to drain for 60 minutes. Discard liquid.
Pie pumpkins: Smaller than a standard carving pumpkin, these cuties are also known as sugar pumpkins. Specific varieties include: Baby Pam, Ghost Rider, Autumn Gold, New England, Cinderella, and Fairy Tale. They're grown specifically for cooking, so the flesh is denser, more plentiful, and less stringy than a jack-o-lantern pumpkin. Don't confuse the pie pumpkins with the tiny gourd pumpkins, though (those can't be turned into purée).
Yield: One fresh (3-pound) pumpkin makes about 2 cups of pumpkin puree, as much as one (15-ounce) can from the store.
Storage: Store fresh purée in the refrigerator and use within 1 week.
Freezer: Scoop into a freezer bag or glass jars (leave 1/2 inch head space for expansion), label, date, and freeze for up to 3 months. Thaw overnight in the refrigerator.
Other squashes: Use this technique on other squash, too: Hubbard, Kabocha, butternut, or acorn. Canned pumpkin is actually made from Dickinson squash because it tastes like pumpkin.
Roasted pumpkin seeds: If you saved your seeds for roasting, toss the clean, dry seeds with 2 tablespoons olive oil and 1 teaspoon salt. Roast on a baking sheet at 350 degrees for about 15 minutes, stirring often.