I was inspired by chicken cordon bleu for this dish, but was unable to will myself to do any breading. I found that the chicken does quite well without it, so that's just one more excuse not to bread anything. Perhaps a light sprinkling of cornstarch might be nice, so I'll try that next time.
Clean the chicken breasts and remove the skin and the supremes. Remove the breast-bone.
In a small mixing bowl, combine the soya sauce and the sesame oil. Let the chicken marinate in the mixture for about five minutes.
Remove the chicken and remove excess marinade. Then slit a pocket in each breast.
Stuff each breast with some rosemary, then a slice of prosciutto, then some cheese.
In a medium-hot skillet, put in some oil. Then arrange the chicken breasts in the pan. Sprinkle the remaining cheese on top.
Place the skillet in the oven, underneath the broiler. Cook for about 5 minutes, or until golden brown.