In a LARGE black cast iron Dutch oven, melt the butter over medium heat and saute' the smoked sausage, onions, celery, bell pepper, garlic, and green onion tops until all of them are tender.
The one thing you want to remember is to keep the butter hot, but don't let it burn (and don't let the garlic burn either or it will turn bitter).
I also suggest that you keep stirring the mixture to cook it uniformly.
Next, stir in the parsley.
Then gradually stir in the chopped oysters, the oyster liquor, and the turkey pan drippings. Notice I said to gradually stir. The reason for this is that you do not want to reduce the heat, lowering the cooking temperature will cause excessive water to be released from the oysters and you'll have to add too much bread to the finished dish.
Now cook the oysters gently over medium high heat for about 4 minutes, stirring all the while.
And when all the ingredients are well mixed, drop in the poultry seasoning, basil, thyme, seafood seasoning, black pepper and salt. About the salt; taste your raw oysters to see if they are naturally salty before adding the prescribed amount.
You may have to reduce additional salt if nature has provided her own.
At this point, cover the pot, lower the heat, and simmer the mixture for about 5 minutes to allow time for the flavors to marry.
This is one of the secrets to making a really good oyster dressing. Don't rush or skip this step!
After the simmering process is done, remove the pot from the fire and begin adding the bread chunks a few at a time.
Note that you do not have to add all four cups.
If you want your dressing moist, stop adding bread when you get to the texture you desire.
If you want a drier stuffing, add all four cups, even a little more if your taste and needs dictate.
Now taste the dressing again and make your final seasoning adjustments.
The objective is to get the bread to absorb all the pan liquor, thereby binding everything together.
When, in your estimation, the dressing is ready (it shouldn't be soupy, but it shouldn't be dry either), allow it to cool slightly. Then rapidly stir in the raw egg to tie everything together and cover it for a few minutes to let it set up.
This is where the richness comes in and it's how the final blending brings out full flavor.
Oh, and if by chance you've miscalculated and made the mixture a bit too dry, just pour in a little extra turkey drippings.
The only thing left to do is to transfer the dressing right from the Dutch oven to a buttered casserole dish, generously sprinkle the top with the buttered cracker crumbs, drizzle on a little extra melted butter, and bake it for about 25 minutes uncovered in a 375°F oven.
Fresh bread chunks are better than dried crumbs in your oyster dressing because they tend to cook up fluffy rather than pasty. So to make fresh bread chunks, just take fresh sliced bread or French bread and pull apart small bite-side pieces.
To make your buttered cracker crumb topping, simply drop regular saltine crackers into the processor and, while the blades are spinning, pour in a couple of tablespoons of melted butter.