Add the mushrooms and scallion to the skillet and cook over high heat, stirring occasionally, until just softened and beginning to brown, about 3 minutes. Carefully add the whisky and ignite with a long match. Cook until the flames subside. Add the stock and cook until reduced by half, scraping up any browned bits from the bottom of the pan, about 5 minutes. Add the cream and simmer just until slightly thickened, 1 to 2 minutes longer; season with salt and pepper. Add the veal, turning to coat. Transfer to the platter and serve.