1. Preheat oven to 350 degrees F. Wipe pumpkins clean and put in the center rack of the oven on a baking sheet. Bake for 1 1/2 hours. Let cool.
2. Cut in 1/2 and scrape out seeds. Cut the pumpkin pieces into strips and remove the skin with a sharp knife. Puree in a food processor or blender until very smooth.
3. Add the sugar and spices and blend until well incorporated. Process in batches if necessary. Taste test and adjust the sugar and spice as needed.
4. There are 2 ways to cook the pumpkin down. The usual way is to put it in a heavy saucepan on the stove. Simmer for about 1 hour until reduced and thickened, stirring every so often.
5. An even easier way is to put the puree into a crock pot on medium heat and let it simmer for several hours, or even overnight. Store in glass jars in the refrigerator for up to a week.
Source of recipe: I wrote this recipe (although all pumpkin butter recipes are similar). Raw on $10 a Day (or Less!)