Lightly pound veal cutlets with a meat mallet until flattened. Place a slice of prosciutto on each cutlet and top with a sage leaf. Secure with a toothpick. Season with pepper.
In a large skillet, heat butter. Add cutlets, prosciutto side down, and sauté about 2 minutes. Turn and sauté another 30 seconds. Remove cutlets from pan and keep warm.
Deglaze pan juices with white wine, season to taste and pour sauce over cutlets.