Preheat oven to 375 degrees. 

Place chunks of butternut squash on a large baking sheet. Drizzle with olive oil and season with salt, pepper, herbes de provence, nutmeg and paprika. Toss to coat evenly. Roast for 45 minutes. 

Heat butter in large stock pot over medium high heat. Once butter has melted and begins to bubble, add onion and saute for approx. 5 mins or until translucent. Add garlic and saute for one minute or until fragrant. Add carrots, celery, roasted butternut squash and bay leaves. Deglaze the pan with sherry and continue cooking on high until the liquid has evaporated. Add broth and bring to a boil. Cover and reduce heat to low. Cook for 45 mins. Remove bay leaf and puree with an immersion blender until smooth and creamy. Add sour cream, puree again and adjust seasoning to taste.