All pumpkins can be cooked, but some are better for it than others. Here are some pictures of various pumpkins and the thickness of their flesh. The thicker the flesh, the more pumpkin puree from the pumpkin. As a rule of thumb, those big round pumpkins we love to make into jack-o-lanterns, aren't the best for pumpkin Puree. The fancy, squished looking, cinderella style pumpkins have a thicker layer of flesh.
So feel free to buy those pretty Cinderella Pumpkins, put them on your doorstep and enjoy them. In November cut them up and cook them.
This can't be done with pumpkins you have carved for jack-o-lanterns because they begin to go bad, or ones that have gotten soft or mushy even if they weren't cut. Try to keep them out of water puddles, and turn them from time to time so all sides get air.
You can soften the pumpkin in the microwave (if it will fit) for 5-7 minutes, but pierce the skin with a knife or ice pick before cooking. After slicing the pumpkin, you can put it cut side down on the cookie sheet and roast at 350° for an hour. Then test to see if it is tender. Add time if necessary.
When the pumpkin gets tender, remove it from the oven, cool it, and then scrape it out. Sometimes, the skin will have lifted from the flesh and it is easier to use your fingers and just pull the skin off.
Since different pumpkins are different flavors, colors and textures, I like to blend several pumpkins together. Put them in a bowl and process them through the food processor or blender to make them smooth.
Put the puree in zip top bags - a scant 2 cups to be equal to a can. Remove all the air and press the bag flat to help with freezer space.
You could also use something similar to these 1 cup silicone molds.
Frozen pumpkin can be kept for many months and used in any of the pumpkin recipes on this site. You could try: