Using a sharp knife, make a slit in the side of each chicken breast, to make a little pocket.
Mix together the cream cheese, garlic, herbs and some salt and pepper.
Lay 2 slices of the Parma ham on a cutting board and place one of the chicken breasts on top. Spoon one-quarter of the cream cheese mixture into the chicken breast, then wrap around the Parma ham to seal the pocket. Repeat with the remaining ham, cream cheese and chicken to give 4 parcels. Place in a roasting tin and bake in a preheated oven, 200˚C (400˚F), Gas Mark 6, for 25 minutes.
Meanwhile, chop the remaining Parma ham and fry in a lightly oiled frying pan over a medium heat for 1–2 minutes. Add the leeks and stir-fry for 2–3 minutes, then stir in the fromage frais and some salt and pepper.
Serve the chicken with a crisp green salad and the bacon and leek sauce.