The fish fillets are cut into cubes. Flavor with salt, pepper and garlic. Add fresh rosemary leaves, basil and olives.
Strain the fillet and additional items and distribute on the shells. Cover with a layer of gratin, made from breadcrumbs, salt, chopped fresh basil, rosemary and olive oil. The shells are wrapped individually in foil and baked in a very hot oven.
Remove foil and grill for about 5 minutes. Serve with a slice of lemon, or freshly squeezed lemon juice.