Finely chop all herbs together on a board.
Mix herbs with garlic, parmesan, butter, salt, and pepper into a smooth paste.
Overlap ham on clingfilm, spread the paste, roll into a sausage shape, and chill for 30 minutes.
Butterfly the lamb cutlets and flatten with a meat tenderiser.
Discard clingfilm and cut the chilled butter filling into 2.5cm slices.
Place a filling slice inside each cutlet and fold to seal carefully.
Arrange cutlets on a foil-lined tray and season with salt and pepper.
Grill under high heat for 2 to 4 minutes per side depending on preferred doneness.