Preheat the oven to 180°C/ 350°F/Gas mark 4.
Put the chicken fillets, bottom side up, between two pieces of cling film. Working out from the centre, pound each piece lightly with a meat mallet. Remove the cling film. Put a ham slice, a cheese slice and a few tomato slices on each piece.
Sprinkle each fillet lightly with the sage, and roll up Swiss-roll style. Press to seal well.
Combine the breadcrumbs, Parmesan and parsley. Dip the chicken in the butter, then roll in the breadcrumbs. Bake in a lightly oiled dish for 40–45 minutes.