Make cuts along the fillet and turn the chicken inside out. Salt and pepper the fillet to taste, brush each piece with olive oil.
Place tomatoes on one half of the fillet, then top with mozzarella and basil leaves. Cover the filling with the other half of the meat, then secure with skewers.
Place the blanks in a mold and bake at 180°C in the oven for about 30 minutes.