Slice off the stem end of the pumpkin 2 1/2 inches from the top, reserving it; scrape out the seeds and the membranes, reserving the seeds for toasting if desired, and brush the inside of the pumpkin with the butter.
Top the pumpkin with the reserved stem end, bake it in a shallow baking pan in the middle of a preheated 375F. oven for 1 1/2 hours, or until the
Pulp is tender, and let it cool in the pan until it can be handled.
Discard any liquid that may have accumulated in the pumpkin, scoop out the
Pulp, and in a blenderpuree it in batches, transferring it as it is pureed to a large sieve or colander lined with overlapping large coffee filters and set over a large bowl. Cover the surface of the puree with plastic wrap and let the puree drain, chilled, overnight.