Preparation

• 在4-quart平底锅,将保留虾shells, carrot, celery, onion, and bay leaf. Add 4 cups of water. Bring to a boil over medium-high heat, reduce the heat to a simmer, and cook for 30 minutes. Strain the stock through a fine-mesh sieve and reserve 1/4 cup for the scampi. (Freeze the rest for other uses.)
• Pat the shrimp dry and season with 1/2 tsp. salt and 1/4 tsp. pepper. In a 12-inch heavy-duty skillet, melt 3 Tbs. of the butter over medium heat. Add the parsley, garlic, and lemon zest and cook, stirring occasionally, until the garlic is lightly golden, 1 to 2 minutes. Raise the heat to high, add the shrimp, and cook until they start to turn pink, about 1 minute. Add the wine and cook until reduced by half, 1 to 2 minutes. Add the reserved shrimp stock and simmer until the shrimp are just cooked through, 1 to 2 minutes. Add the lemon juice and crushed red pepper flakes, if using, and stir to coat.
• With a slotted spoon, transfer the shrimp to a serving plate. Whisk the remaining 1 Tbs. butter into the sauce. If the sauce seems thin, simmer it gently for a minute or two to thicken. Season to taste with salt and pepper, pour over the shrimp, and serve with the lemon wedges on the side.