Combine the celery, fennel, onion, garlic, red pepper flakes, 1/2 cup of the whole flat-leaf parsley, some of the EVOO and a little salt and pepper in a large baking dish. Toss to coat veggies with the oil. Add the white wine and stock.
Season the halibut & scallops with salt and pepper, drizzle with remaining olive oil and nestle everything into the baking dish.
Top with the crushed/diced tomatoes then transfer to the oven and roast until the cod is cooked through, about 45-50 minutes. I added the shrimp and muscles after 40 minutes.
NOTE as the muscles where an extra that I added to this recipe my baking dish was not big enough I had to put the muscles into a separate shallow baking dish and I spooned some of the juice over them. So make sure you use a large baking dish,
Slice the bread into large chunks, as I have to watch my sodium intake I do not cook with salt so depending on your taste buds you may have to add salt.
Serve in Large bowls.
Note I had enough left over for lunch the next day so depending on how big your bowls are or how hungry your company is you may get more then 6 servings.