Step 1Place a piece of waxed paper on a cutting board and place a slice of veal on it. Cover the meat with another piece of waxed paper. Using the blunt side of a meat mallet, pound lightly on both sides to flatten and tenderize, being sure not to break the meat. To pound the reverse side, just flip the meat over, sandwiched between the sheets of waxed paper. Flatten all the slices very thinly in this fashion, replacing the waxed paper when necessary. Cut each slice into a piece about 2 by 4 inches and discard the trimmed bits. You should have 12 thin scaloppine.
Step 2Place a sage leaf on each slice, then add a slice of prosciutto the same size as the veal. Roll up and secure with a toothpick.
Step 3In a large skillet, melt 2 tablespoons of the butter with 1 tablespoon olive oil over medium heat. Add half the veal, increase the heat to high, and saute until lightly golden on the bottom, 2 or 3 minutes. Season the meat with salt and pepper as it sautes. Turn the rolled slices quickly to brown the other side for 2 minutes. Transfer the veal to a warmed dish. Add 2 more tablespoons of the butter and the remaining olive oil to the skillet and repeat to cook the remaining veal.
Step 4When all the meat has cooked, add the remaining tablespoon of butter and the water to the pan and stir. As soon as the butter melts, take it off the heat and pour it over the veal. Serve hot.