- 1 medium pumpkin – peeled and cubed
- 5 cups chicken broth, divided
- 6 dried red chile peppers, stemmed and seeded
- 1 teaspoon butter
- 1 large onion, chopped
- 2 pounds leeks, chopped
- 1 teaspoon cumin
- 1 bay leaf
- salt and ground black pepper to taste
- 1 cup buttermilk
- Preheat oven to 425 degrees F (220 degrees C).
- Bake the pumpkin on a baking sheet in the preheated oven until soft, 30 to 40 minutes.
- Combine 2 cups chicken broth and chile peppers in a saucepan over medium-low heat; simmer for 30 minutes.
- Melt butter in a large stockpot over medium heat. Cook and stir onion in the butter until caramelized, about 45 minutes. Transfer to a bowl.
- Cook leeks in the same stockpot until tender, 10 to 15 minutes. Add pumpkin, chicken broth with chile peppers, caramelized onion, remaining 3 cups chicken broth, and cumin. Simmer until flavors combine, about 5 minutes.
- Puree soup with an immersion blender until smooth. Add bay leaf, salt, and pepper. Remove from heat; stir in buttermilk. Discard bay leaf before serving.