The Need To Know Classic That Is: Shepherd's Pie

Let's get this out of the way now - a true shepherd's pie is made with ground lamb; when ground beef is used, it's called a cottage pie. Over time, ground beef became the filling of choice, and lamb was used less frequently. This is why the two names are used interchangeably.  Originating from the British Isles in the late 18th and early 19th centuries, shepherd’s pie was a way for people to save and make their money, and leftover food last longer. Early versions of the dish used a pastry shell at the bottom and top to hold everything together; over time, potato slices were used at the bottom, eventually making their way to the top as mashed potatoes. So if you ever see ground lamb (or ground beef) on what constitutes a sale nowadays, use the recipe below. 

Ingredients

1 kg Russet potatoes, peeled
700 g ground lamb or beef
225 g carrots, diced
200 g canned chopped tomatoes
125 g white mushrooms (optional)
30 g butter
15 g flour
5 g frsh sage, chopped
240 mL beef stock
45-60 mL milk
5 mL Worcestershire sauce
2 onions
2 garlic cloves, crushed
salt and pepper

1. Preheat the oven to 200ºC. Place whatever meat you're using in a large, heavy-bottomed saucepan with no cooking oil, and gently cook until the meat begins to brown.
2. Add the onions, carrots, and garlic and continue gently cooking everything for about 10 minutes. Stir in the flour and cook for a minute or two. Gradually stir in the beef stock and the tomatoes and bring everything to a boil. Add the Worcestershire sauce, the sage, and salt and pepper to taste. Cover and simmer for 25 minutes, stirring occasionally.
3. In another pot, boil the potatoes in salted water until they're tender, then drain thoroughly, and mash, beating in the butter, some salt and pepper to taste, and enough milk to give the potatoes a good consistency for piping. If you don't have a piping bag to spread the mashed potatoes, there are alternate ways to do it.
4. Stir the mushrooms (if using) into the meat and taste and adjust the seasoning if necessary. Pour the meat into a shallow ovenproof dish. Pipe the potatoes evenly over the meat. 
5. Place in the oven and cook for 30 minutes or until it's piping hot and the potatoes are golden brown.