Preheat oven to 375°F. Cut the top off each pumpkin and then cut in half. Scoop out the inside of the pumpkin, seeds and guts. Place on a lined baking sheet. It doesn't matter if the inside of the pumpkin is facing up or facing down. Place in oven for 45 minutes.
You will know the pumpkins are finished roasting when the skins bubble away from the meat of the pumpkin. Remove from oven and allow to cool completely before handling.
Once pumpkins are cooled, peel the skin off and place the meat of the pumpkins inside a food processor or blender.
Begin blending and add 1 Tbsp of water at a time until the pumpkin becomes a smooth puree. Don't add water too quickly, you don't want the puree to be soggy. You want it to be a thick paste.
Once the puree reaches desired consistency, place in a container. The puree can be kept in the fridge for up to a week or freeze for up to a year. You can also can it.