Preheat oven 425°F.
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 fish with salt and pepper, drizzle with remaining EVOO and nestle everything into the baking dish.
Top with the crushed tomatoes then transfer to the oven and roast until the cod is cooked through, about 45-50 minutes.
Slice the bread into large chunks, place them on a baking sheet and toast in the oven or under the broiler until lightly charred. While bread is toasting, chop remaining parsley together with the lemon zest to create a gremolata garnish.