Adjust oven rack to the middle position and preheat the oven to 400°. Cook the bacon a large saucepan or dutch oven, over medium heat until crisp, transfer to a paper-towel-lined plate with a slotted spoon; set aside. Add the onions and celery to the bacon fat left in the pan; cook over medium heat, stirring occasionally, until softened. Add the garlic and cook until fragrant, about 30 seconds. Add the flour and cook, stirring constantly, until golden, about 1 minute. Whisk in the clam juice, cream, and wine. Add the thyme, bay leaves, potatoes, and crisp bacon. Bring to a boil, cover, and reduce the heat to low; cook, stirring occasionally, until the potatoes are just tender, 30 to 35 minutes. Discard the bay leaves and season with salt and pepper to taste. Stir in the cod and transfer to a 9 by 13-inch baking dish and wrap tightly with aluminum foil. Bake until the cream has thickened and the cod is fully cooked, about 25 minutes. Sprinkle evenly with oyster crackers and parsley. Serve immediately with lemon wedges.
