Shrimp stock. Heat the olive oil in a large heavy pan over high heat until it begins to smoke. Add the shrimp shells to the pan and cook, stirring constantly, until they turn deep orange and are just beginning to brown, 3–4 minutes. Remove from heat briefly to add the wine to the pan, then boil it over medium heat until all the liquid is evaporated. Add the stock, saffron, fennel, onion, bay leaves, and sage. Bring to a boil, then reduce the heat to low. Partially cover the pan and simmer gently for 30 minutes. Strain the stock through a fine sieve, pushing down on the solids to extract all the liquid. Rinse out the saucepan and pour the stock back into it.

Soup: Whisk the pumpkin, cream, salt (omit if using canned stock), chipotle, and vinegar into the shrimp stock. Season to taste with salt and pepper. Refrigerate until close to serving time.

Reheat gently, uncovered, and simmer for at least 10 minutes.

Shrimp: Heat olive oil and butter over medium heat, add sage and stir for a minute, then add shrimp. If the shrimp is raw, cook tossing often until the shrimp is just cooked through, pink, and no longer translucent, but not curled into a circle. They should still have a tender snap when you bite into them. If the shrimp is ready-to-eat, stir to heat through.

Pour the reheated soup into a tureen, arrange the shrimp on top, and serve.