Autumn harvest time means observing many pumpkins on display at local farmers markets. Choose what are known as pie pumpkins to make pumpkin soup. They are smaller and less grainy than jack-o-lantern pumpkins. Pie pumpkins are usually 8 to 10 inches in diameter and they have sweeter taste. Home gardeners begin to harvest pumpkins in September when their leaves start to wither and lose color. The pumpkins are ripe and ready when the stem begins to dry away from the vine. Leave a foot or more of vine on each pumpkin and it can be stored safely for the winter in a cool, dark place.
Wash the exterior of the pumpkin with warm water but no soap. Cut the pumpkin in half and scoop out the seeds with a heavy ice-cream scoop. Put the pumpkin in a casserole dish with a lid. Add 3 cups water and bake for 45 minutes to 1 hour at 350 degrees F.
Remove the pumpkin pulp from its skin and place it in a bowl. Mix for three to four minutes with a hand mixer or hand blender.
Saute the diced onions, grated carrots and chopped celery in a pan with butter until tender.
Add the pumpkin and remaining ingredients except the half-and-half. Cover and simmer for 10 minutes, stirring occasionally.
Add the half-and-half, heat through and serve warm.