Rinse chard, cut out stalks and and cut the leaves into wide strips. Blanch leaves in boiling salted water for about 1-2 minutes. Shock in ice water and drain.
Heat 1 tablespoon butter in a pan, add chard and sauté briefly. Season with nutmeg, salt, pepper and lemon juice.
Heat in 2 tablespoons butter in a skillet. Fry potatoes until golden brown over low heat. Season with salt and pepper.
Poud veal cutlets flat with a meat mallet. Top each with 2 sage leaves and a slice of prosciutto. Secure with toothpicks, season with pepper and fry on both sides until golden brown in 2 tablespoons butter for 2-3 minutes. Remove from the pan and arrange on warmed plates. Deglaze pan with white wine, bring to a boil briefly and drizzle over the veal. Serve with potatoes and chard.