Cut a slit along the length of each chicken breast to make a large pocket. Spread the ricotta in the pockets and top with basil leaves and sun-dried tomatoes. Press the chicken together firmly to close the pockets. Season the chicken with salt and pepper.
Heat the oil in a large frying pan, add the chicken breasts, skin side down, and fry for 15 minutes, turning once, until golden and the chicken is cooked through. Serve with spinach and new potatoes and the juices from the pan.