1 pumpkin....depending on how much puree you want size is up to you.(Mine was about 8lbs)
Cut your pumpkin in half with a large knife and scoop out all the seeds and "guts"
Chop it into several large chunks , remove the entire stem and "core"...You can skin it first but I find doing it after it is steamed is much easier.
Place it in a steamer over medium high heat.
My steamer only held 1/2 the pumpkin at a time.
Steam it until very tender(about 15 minutes)
Remove and allow to cool until you can comfortably handle it to remove the skin.
Chop into smaller pieces and place in a food processor
Turn it on high and Puree it up. Keep going until all the chunks are gone.
Cool completely and freeze.... 15 oz can = approx 1 3/4 cups so I like to divided it up and freeze it in "can" size.
My pumpkin yielded 10 cups. So about 5 3/4 "cans"