Preheat oven to 350º F.

Clean and remove heads and shells from shrimp, leaving tails. Split shrimp; remove veins and open flat. Sauté onion and green pepper in 4 Tablespoons butter until soft, but not brown, about 5 minutes. Add crab meat, dry mustard, Worcestershire sauce, salt and mayonnaise. Set aside.

Make white sauce using remaining 2 Tablespoons butter, flour and milk. Add to crab meat mixture along with sherry; mix well. Stuff the butterflied shrimp with crab meat mixture. Dot with extra butter. Sprinkle with Parmesan cheese and paprika. Arrange in a shallow baking dish and bake at 350º F for 25 to 30 minutes. Yield: 4 to 6 servings.