Pasta with Oysters and Shrimp

* raw and peeled (about 32 to 40 per lb) ** chopped, for garnish Heat a large frying pan and add the oil. Stir in the flour and cook this mixture until it is the color of light peanut butter, being careful not to burn it. Add the onions and suate until limp. Stir in the anchovy paste and the half-and-half, stirring carefully to avoid lumps. Turn to a light simmer and add the Tabasco, Worchestershire sauce and thyme, and simmer for 10 minutes. Add the oysters and shrimp and heat for a few minutes. Do not overcook the seafood. Add salt and pepper to taste and serve over the hot pasta. Garnish with chopped green onions.