How to Make It
In a medium saucepan, melt the butter in the extra-virgin olive oil. Add the scallions and cook over moderate heat until softened, about 2 minutes. Add the heavy cream, vegetable stock and saffron and bring just to a boil. Simmer over moderately low heat, stirring occasionally, until the sauce is reduced to 1 3/4 cups, about 15 minutes. Strain the sauce through a fine sieve into a small saucepan and season with salt and pepper. Keep the saffron sauce warm over low heat, stirring occasionally.
Meanwhile, in a large, deep saucepan, bring the ale just to a simmer. Add the shrimp and poach over moderate heat until they are just cooked through, about 3 minutes. Using a slotted spoon, transfer the shrimp to a plate, pat dry and season with salt and pepper.
In a medium saucepan of salted boiling water, blanch the asparagus pieces until they are crisp-tender, about 2 minutes. Using a slotted spoon, transfer the asparagus to paper towels to drain.
Spoon the saffron sauce into shallow bowls, top with the blanched asparagus and poached shrimp and serve.
The saffron sauce can be refrigerated overnight and gently reheated before serving; add a little water or vegetable stock, if necessary.