I don't know if there are any "rules" for this dish, but here is my latest version:
-a bunch* of potatoes
-milk and butter for mashing
-1 lb. ground beef
-fresh herbs (optional)
*By now you've noticed my vague amounts. It really depends on the size of the pan and which ingredient proportions you prefer. If you don't like "eyeballing," you can always look up a similar recipe and use the suggested amounts there. As you can see, I used a lot of potatoes this time...it just happened.
Preheat oven to 350 degrees
1) Peel potatoes and put them on to boil.
2) While potatoes are cooking, chop the onion and saute it.
3) Brown the ground beef for a few minutes.
4) Add a little water and flour or tomato sauce to create some juices.
5) Saute the veggies by either adding them to the beef or in a separate pan.
6) Drain potatoes, mash with milk (or powdered milk and water), sauteed onions, and herbs. Salt to taste.
7) Spread meat and veggies in baking pan (separately or mixed; whichever you prefer).
8) Spread mashed potatoes over them.
9) Pour beaten egg on top.
10) Bake at 350 for 25-30 min., until bubbling/golden.