Preheat oven to 400. Take pumpkin and halve, scraping out seeds. Cut into wedges and roast (cut side down) for 40-50 minutes, or until flesh is easily pierced with fork. Scrape out flesh and puree in food processor until smooth. Measure out 5 cups. Set aside.
In a large saucepan over medium-high heat, add 1 Tablespoon butter and saute carrots until tender, about 5 minutes. Add serrano pepper and sage and stir until aromatic, about 1 minute.
Add pureed pumpkin, stock, cream, milk or coconut milk and remaining ingredients to saucepan. Bring to boil, and simmer 20 minutes. Puree with immersion blender, or in batches using a food processor. Simmer for an additional 5 minutes, adding more sweetness or salt/pepper to taste.
Salsify Garnish: A quick word on salsify: It is a mild-flavored yet very tasty root vegetable that resembles a carrot. Peel off outer layer and peel in thin strips. Saute with 2 Tablespoons butter until crispy, about 5-8 minutes. Transfer to paper towel to cool. Set aside.
Ladle individual portions; top with salsify garnish. Serve hot.