Wash the pumpkin and cut in two. Clean out the stringy pulp and seeds and cut the rind into 2 cubes, trimming off the outer rind as you go. Cover with water in a dutch oven and bring to a boil. Reduce to a simmer, cover and cook until pumpkin is fork tender. Drain off the liquid and discard. Mash the remaining pulp with a potato masher. To every two cups of pumpkin pulp, add 1 cup of sugar and 1/4 tsp. cinnamon and 1/4 tsp. freshly grated nutmeg. Place the mixture in a large flat baking pan, such as a meat roaster or a 13 x 9 x 2 pan. Bake uncovered in a 325 degree oven until the mixture is thick, golden, and the consistency of apple butter. Stir often to prevent sticking. (This may take 2-3 hours depending on the moisture in the pumpkin) Fill hot sterilized jars with boiling hot pumpkin butter, leaving 1/4 inch headroom. Adjust lids and process according to manufacturers instructions. By boiling water bath, process 10 minutes. The yield depends on the size of the pumpkin. Although this recipe calls for a large pumpkin, I like to make the butter using a couple of small pie pumpkins. I believe they have a sweeter and richer flavor.