Preheat oven to 350 degrees.
Cut the bread into cubes. Spread them on an even layer on a baking sheet. Bake for about 10 minutes until the bread is toasted but not yet brown. Remove the bread from the oven and allow it to cool. Do not turn the oven off.
Melt 1 stick (8 tablespoons) of the butter in a stock pot over medium high heat.
Add the onion, celery and green bell pepper. Lightly season with a little salt and pepper. Saute until the vegetables are tender, about 7 minutes.
Add the minced garlic and sauté for and additional 30 seconds.
Add the oysters and cook until they are opaque and the edges begin to curl.
Add the sausage and parsley and cook until heated through, about 2-3 minutes more. Remove the pot from the heat.
Add the cubed bread to the pot. Stir to coat the bread with any juices in the pot. The bread should be moist but still keep its shape, not soggy. Use the reserved juice from the oysters if necessary. Add a little bit of the chicken broth if you don’t have enough oyster juice.
Spread the dressing into a greased 8 x 8 casserole dish or 11-inch cast iron skillet.
Spread the crushed saltines over the top of the dressing.
Melt the remaining four tablespoons of butter. Drizzle the butter over the top of the crackers.
Bake for 30 minutes until the top of the dressing is toasted and the crackers start to turn golden brown.
Allow the dressing to cool for 15 minutes before serving.