Preheat the oven to 375 degrees. Butter a large gratin dish or casserole with a tablespoon of the melted butter.
Wash, stem and coarsely chop the sorrel. Peel and thinly slice the potatoes. Layer half the potatoes in the gratin dish. Season with salt, pepper and nutmeg, add a layer of the chopped sorrel and parsley and then top with a remaining layer of potatoes.
Season with salt, pepper and nutmeg and add enough stock and milk to almost cover them. Drizzle the surface with the remaining butter and sprinkle with the grated cheese. Bake about 1 hour until the surface is nicely browned and the liquid is nearly absorbed. Serve garnished with more chopped fresh parsley.
Nutrition information per serving:
Calories225Fat7 gSodium295 mg
Carbohydrates34 gSaturated fat4 gCalcium155 mg