Place pumpkin on a parchment lined rimmed baking sheet and place into oven. Bake until a paring knife can easily be inserted into the skin of the pumpkin, about 1 hour.
Remove the pumpkin from the oven and allow to cool for about 30 minutes. Slice the pumpkin in half with a knife, and then scoop out the seeds and membrane from the inside of the pumpkin, saving the seeds for roasting.
Scoop out the soft pumpkin flesh with a large spoon and place into blender and puree. Strain to remove any remaining stringy pieces and store in an airtight container in the refrigerator for up to three days or in the freezer for several months.