In a large pot, mix together pumpkin, broth, onion, garlic, cumin, salt, pepper and cayenne. Bring to a boil over medium-high heat. Reduce heat, cover and simmer for 25 minutes.
Stir in butter and chipotle pepper; simmer 1 to 2 minutes longer, stirring constantly.
Stir in sour cream, keeping on low heat for 2 to 3 minutes longer.Makes 4 Source: