Beat the egg, pepper, stock granules and Worcester sauce or Maggi® together in a bowl.
Cut the chicken breasts in half, and sandwich between cling film. Pound lightly with a rolling pin. Remove from the cling film and dip in the mixture of egg and seasoning. Marinate for at least 2 hours.
Combine breadcrumbs and flour on a plate then toss the chicken in the breadcrumbs to coat.
Heat the oil over medium-high heat in a large frying pan. Fry chicken on each side until golden brown and no longer pink in the centre. Serve immediately.