Leaving the head on the whole fish, snip out and discard the gills. Rinse the whole fish in running cold water. Insert the tail of the fish through the opening left by the discarded gill, forming the fish into a heart shape. Place a peeled clove of garlic and a few rosemary leaves in the ventral cavity of each fish. Place in a baking dish and pour the olive oil over the fish. Put in the refrigerator and allow to marinate for hour. Turn once or twice.
Mix the breadcrumbs with plenty of freshly ground pepper and a few rosemary leaves and salt to taste. After draining the oil from the fish, sprinkle 1/3 of the breadcrumbs on the bottom of the baking dish. Pat breadcrumbs on the fish and place into the dish. Bake about 20 minutes in a 400 oven. Sprinkle the remaining oil on the fish every 5 minutes. Serve immediately. Makes 4 servings.