Arrange the sliced potatoes in the bottom of a pan or casserole dish, top with the cooked ground beef, then a layer of sliced ...

Related: 10 Leftover Turkey and Chicken Casserole Recipes To Get the Most Out of Your Bird Related: 52 Low-Carb Ground Turkey ...

Mix the mustard, horseradish and double cream (if using) in a bowl until well combined. Just before serving, stir it into the beef casserole. Serve with mashed potatoes and steamed vegetables.