Place pumpkin in unheated oven. Make sure to lower oven racks as needed to allow room for your pumpkin. Also, put some foil or a pan on a rack under the pumpkin to catch drips.
Heat oven to 350 degrees and let pumpkin cook until tender. You should be able to poke it with a fork and it should slice into the pumpkin like it's butter. My pumpkin took 2 hours to become tender but cooking times will vary based on the size of your pumpkin.
Once pumpkin is finished, turn off the oven and leave the pumpkin in there for at least an hour and a half to cool. Once pumpkin has cooled, remove from oven and slice into manageable sized pieces.
Use an ice cream scooper (or spoon) to remove pumpkin from outer shell. Put pumpkin in blender and blend until pumpkin turns into a puree. If needed, add a little water (or stock or milk) to help the pumpkin blend.
Spoon into 1, 2 or 4 cup bags based on how much you will need in future recipes. Once completely cooled, place bags in freezer until ready for future use.
Servings: Several cups depending on size of your pumpkin
Prep and Cooking Time: ~2 hours bake, 1 1/2+ hour cool, 1 hour prep