Preheat & Prep. To start, preheat oven temperature to 400 degrees F. Line a sheet pan with parchment paper. (This makes for easy clean-up, prevents sticking, and helps the pumpkin steam.)
Wash & Cut The Pumpkin. Then, wash the outside of the pumpkin very well, removing any dirt or debris. You want it squeaky-clean! Turn the pumpkin over, starting with the bottom of the pumpkin and use a sharp knife to cut the pumpkin in half, toward the stem. (I find this is easier than starting at the stem end.) Carefully pull the pumpkin apart.
Remove The Seeds & Pulp. Using a spoon or your hands, scoop out the pumpkin seeds and most of the stringy pumpkin pulp trapped around the seeds. It's perfectly fine if there are a few strings left, you just want to remove the loose pulp around the seeds. Discard the seeds & pulp, or rinse the seeds to remove the pulp to dry and roast later!
Roast The Pumpkin. Place the pumpkin cut side DOWN onto the prepared baking sheet and roast the pumpkin 45-60 minutes, or until the pumpkin starts to collapse on itself, and the pumpkin gives way very easily when pressed with a fork. The shell of the pumpkin may start to brown on the outside, this is fine!
Puree. Cool the roasted pumpkin until it's cool enough to handle, then scoop out the roasted pumpkin flesh from the pumpkin shell. Work in batches to add the roasted pumpkin to a blender or food processor. Puree until smooth. If using a blender, stop regularly to stir so you don't overwork your blender motor!
Strain. If possible, place a fine-mesh sieve over a bowl and add the pumpkin puree to the sieve. (Do NOT press down on the puree, just add it to the sieve!) Let the excess water drip down through the sieve into the bowl to remove excess moisture from the puree. This will give your baked goods & recipes the best texture!
Enjoy or Store. Use pumpkin puree in your favorite pumpkin recipes, or store for later. Chill in an airtight container in the fridge 2-3 days, or freeze up to 3 months. (You can freeze up to 6, but I find the flavor is best when used within about 3 months.)