Preheat oven to 350 degrees F.
Wash the outside of the pumpkin and dry.
With a sharp knife, cut the pumpkin in half. Using a large spoon, scrape out the inside stringy parts of the pumpkin, along with the seeds. Scrape as much of the stringy bits off as you can.
Again with the knife, proceed to cut each half of the pumpkin into smaller sections.
Lay the sections out, face down, onto a parchment lined baking sheet. (Depending on the size of the pumpkin, you made need two baking sheets.)
Bake the pumpkin for 1 - 1 ½ hours, or until VERY soft.
Remove and let cool.
When cool, cut or scrap the pumpkin meat off the rind.
With a blender or a food processor, blend the pumpkin until it is very smooth. Sometimes a bit of water may be required to get the processor going smoothly, but try to only use what is necessary. You don’t want the puree too watery.
When you’re pureed the entire bunch of pumpkin pieces, store the puree into an airtight container.