Put butter and onion in frying pan and cook on moderate to low heat until translucent. Puree. Add pumpkin, salt, and chicken broth. Stir well and bring to boiling. Add in 1/2 cup brown sugar, 1 teaspoon cinnamon, 1 teaspoon pumpkin pie spice, and pinch of nutmeg to the base. Keep heat at boiling to deepen the flavor. This can at this point be pressure canned.

For serving, heat up the pumpkin soup base and add 1 cup milk. Just before serving, add the 2 cups of half and half and adjust seasoning to your taste.