Special equipment: a rectangular casserole dish
Preheat the oven to 400 degrees F.
In a large oven proof skillet heat the olive oil over medium heat, add the potatoes and cook until tender, about 8 minutes. Add the onions, season with salt and pepper, cover and cook for 5 minutes. Add the white wine, simmer for 1 minute. Add the fish stock and bring to a boil and reduce the liquid by 1/2. Taste and adjust seasoning, if required. Portion the potatoes and onions into 6 stacks in the skillet.
Season the red snapper with salt.
Place one fillet, skin side up, on each stack of the potato onion mixture. Scatter the roasted garlic, cherry tomatoes, black olives, thyme, and rosemary around the stacks. Cover the skillet with a lid or foil. Bake for 25 to 30 minutes.
Serve in shallow bowls with the cooking juices. Garnish with chopped parsley.
Rinse the fish bones thoroughly in several changes of cold water. In a large stock pot place the fish bones and add the cold water. Bring to a slow simmer over medium heat.
Skim the surface of foam and impurities to produce a clear, clean, fresh tasting stock.
Add the leek, fennel, onion, celery, parsley, thyme, peppercorns, and bay leaves. Reduce the heat to medium-low and simmer for 20 minutes.
Strain the stock and cool. Store the stock in the refrigerator for up to 4 days or in the freezer for up to 1 month.
Take 20 cloves of peeled garlic sprinkle with 1 tablespoon olive oil and wrap in foil. Place in a preheated 350 degree F oven and roast for 15 to 20 minutes.