Cut veal scaloppini in half. Place one sage leaf on each piece of veal, then wrap both in one slice of prosciutto. Dredge in flour.
Heat three tablespoons (45 milliliters) butter and olive oil in a pan on medium-high heat. When butter is hot and golden in colour, add two to three scaloppini, being careful not to overcrowd the pan. Fry just until pink of veal disappears. Flip scaloppini once, allowing for prosciutto to crisp. Transfer cooked scaloppini to a platter and repeat with next batch.
When all scaloppini have been cooked and transferred, add wine to pan, scraping brown bits from the bottom. Reduce wine for a few minutes. Add veal stock and reduce for another few minutes. Place veal back in pan with sauce for one minute, then transfer veal to plate. Add remaining tablespoon (15 milliliters) of butter to sauce in pan, whisking to combine, then drizzle sauce over scaloppini.