Clean, wash and halve the leek. Dice the ham slices.
Fry the leek sticks in a large pan in a little butter, cut side down, until they are lightly brown. Add the chicken stock and lightly salt (do not use salt for instant chicken stock!). Simmer gently for about 10 minutes, until the leek is cooked through and the broth is reduced to about half.
Put the leek in a buttered casserole dish or gratin dish. Pour the reduced broth over the top, sprinkle with diced ham and parmesan and top with flakes of butter.
Briefly toast under the heated grill until the ham is crispy and the cheese has melted. Serve immediately.
A light lunch or dinner with bread or as a side dish to other dishes.