If you are using a frozen fillet, you need to defrost it first.
Preheat the oven to 180 degrees C.
Dry the fish and season on both sides with salt and pepper.
Prepare a small baking tray. Spray it with oil spray. Place the fillets on the tray.
Slice the large tomato and place the slices on top of the fillets. Then put few chopped basil leaves on top, followed by chopped olives and in the end covered by slices of mozarella cheese.
Place it in a preheated oven and bake for about 25 minutes (depending on your oven) or until the fish is cooked through and the cheese has melted and started to have golden colour in places.