Shell the shrimp but do not remove the last small segment of shell or tail. Devein the shrimp and rinse well under cold water. Pat dry thoroughly with paper towels.

Preheat broiler to highest temperature. In a shallow flame-proof baking dish or pan - just large enough to hold the shrimp in one layer, melt the butter over low heat and be careful not to let it brown. Stir in 1/2 cup of olive oil, lemon juice, shallots, garlic, salt and a few grindings of pepper. Add the shrimp, turning them in the butter and oil until they glisten on all sides.

Broil them 3 to 4 inches from the heat for 5 minutes, then turn the shrimp over and broil for 5 to 10 minutes longer or until lightly browned and firm to touch. Be careful NOT TO OVERCOOK. With tongs, transfer shrimp to a heated serving platter, pour the sauce from the pan over them and sprinkle with chopped parsley. Garnish with lemon quarters and serve. To serve 6.