I first tasted this a long time ago at a festival at the Queens Farm Museum. They were nice enough to share their recipe but it just didn't taste the same as theirs. I've tweaked the recipe a bit over the years and we enjoyed it tonight with turkey sandwiches.
Melt the butter in a soup pot. Add the onions and saute gently for about 10 minutes. Add the pumpkin, salt, pepper, brown sugar, nutmeg and allspice. Slowly add the broth. With an immersion blender, blend until smooth. (or in a blender). Heat thoroughly, then add cream. Heat again but do not boil. I like to garnish it with a dollop of sour cream and a little freshly ground nutmeg.
This can also be made in your crockpot. Cook on low for 3 hours, add cream and cook for another hour.