How to Make It
Lay the pork slices on a work surface and pound to 1/4-inch thickness. Season with pepper. Set a sage leaf in the center of each cutlet. Top each cutlet with a slice of prosciutto; thread 2 toothpicks through each one to secure the prosciutto.
In a very large skillet, heat 2 tablespoons of the olive oil until shimmering. Add 1 tablespoon of the butter. Arrange 6 of the cutlets in the skillet, prosciutto side down, and cook over moderately high heat until the prosciutto is crisp, about 1 minute. Turn the cutlets and cook until barely pink in the center, about 3 minutes. Transfer the cutlets to a warm platter. Wipe out the skillet and repeat with 1 tablespoon of butter and the remaining 2 tablespoons of olive oil and 6 cutlets.
Wipe out the skillet. Add the stock, lemon juice and any accumulated juices from the cutlets and boil over high heat until reduced to 1/2 cup, about 2 minutes. Off the heat, swirl in the remaining 1 1/2 tablespoons of butter. Pour the sauce over the pork cutlets and serve.