Slice the leeks and parsnips into a fine Julienne and place into a shallow oven dish. Season with salt, pepper and nutmeg. Spread the gratin on top and sprinkle with chopped cashew nuts. Bake in the combi-steamer for 15 minutes at 200°C.
Combine lettuce with dressing of walnut oil, lemon juice and chopped parsley. Garnish with radish and finely chopped ham. Serve dishes in separate bowls.
Sprinkle casserole with grated cheese and baked for a while, until the cheese is melted and give golden color and additional cheese flavor.