For the chipotle creme fraiche:
1 cup ruby port
1/2 cup dry red wine
1 teaspoon chopped, canned chipotle chilies
2 tablespoons tomato paste
1 cup creme fraiche or sour cream
For the soup:
Vegetable oil
2-2 1/2 pound kabocha squash, halved horizontally, seeded
8 cups low-salt chicken broth
1 1/2 (7.4 ounce) jars whole roasted chestnuts
2 tablespoons pure maple syrup
Make the chipotle creme fraiche: Combine port, red wine, chilies and tomato paste in heavy small saucepan. Simmer over medium heat until reduced to thick paste, stirring often, about 12 minutes. Transfer to small bowl; cool. Fold in creme fraiche. Cover and chill at least 1 hour and up to 1 week.
Make the soup: Preheat oven to 350 degrees. Brush baking sheet with oil. Place squash halves, cut side down, on prepared sheet. Bake squash until very tender, about 1 hour.
Scoop the squash from skins. Measure 6 cups squash, and transfer to a large pot. (Reserve any remaining squash for another use.) Add broth and chestnuts to pot. Bring to boil over high heat. Reduce heat to medium-low. Simmer soup uncovered until chestnuts are very tender, about 30 minutes. Mix maple syrup into soup. Cool slightly. Working in batches, puree soup in blender until very smooth; return to same pot. Season to taste with salt and pepper.
(Soup can be prepared one day ahead. Cool slightly. Refrigerate uncovered until cold, then cover and keep refrigerated. Bring to simmer before serving.)
Ladle soup into bowls. Top each serving with chipotle creme fraiche.
