Stir the potatoes, soup, sour cream, black pepper and onion in a medium bowl. Spoon the potato mixture into a 1 1/2-quart baking dish. Bake at 350°F. for 30 minutes or until the potato mixture is ...
Mix the cornflour and water and stir into the casserole. Add the leeks and stir well. Top the chicken mixture with the potato dumplings, overlapping them slightly, so they almost cover the filling.