Well, not quite traditional because I can't afford lamb or mutton, so I use ground beef. But this one is pretty easy and versatile--you can change it if you like. I like to use fresh veggies for mine, but you could get away with using frozen if stuck with no time (but if you have the time, chop your own veggies, its really worth it for the flavor and health benefits). My dad loves shepherd's pie and my mom made it at least 3-4 times a year, and whenever she wanted to make Dad happy. I thought it would be appropriate for St. Patrick's Day, and I hope you enjoy!
4-6 potatoes (depending on size--4 large or 6 smallish to medium)
1 lb ground beef
3 carrots, diced
1/2 an onion, finely chopped
2 cloves garlic, finely chopped or grated
1/2 small bag of frozen peas (its the same as shelling your own)
1/2 small bag frozen corn
1-2 tbsp flour
1 c water
1 tsp Worcestershire sauce
pepper, seasoning salt
Cut potatoes into wedges or large dice, then place in large saucepan and cover with cold water (add a little salt too), bring to boil and then continue cooking til potatoes are tender, drain and mash with a bit of butter and some salt, maybe a 1/4 c of milk. Set aside.
While potatoes are cooking, brown your beef, adding onions and garlic when it gets close to done. Do not drain, add flour, and stir til flour coats meat and onions. Add W. sauce, water, pepper and salt. Stir til thickened, and then add corn, peas, and carrots. Cook this mixture over low to medium heat til carrots are tender, but peas are still pretty color of green. Pour mixture into 13x9 baking dish, then top with mashed potatoes. I sometimes top the potatoes with parmesan cheese or breadcrumbs or paprika. It's really up to you.
Bake for 25 minutes at 350 degrees, just til the potatoes get a kind of crust on top and the gravy mixture is a bit bubbly. Everything is cooked so you are just trying to brown the top. Serve by itself or with some other steamed veggies or a salad or some rolls (I forgo the rolls, this one has plenty of carbs on its own).