Hachis Parmentier - Shepherd's pie

Peel, rinse and cut the potatoes into large cubes.
Boil in a sauce pan with a lid for 20 minutes (water with coarse salt).

Meanwhile :
Rinse and chop the parsley leaves.
Peel and slice the onion.
In frying pan with oil, simmer the onion until it becomes translucent.
Chop the meat and add it to chopped parsley.
Add meat and parsley to the pan and mix everything.
Add the broth and cook over medium heat until the liquid evaporates (stop before the mixture starts drying).

Drain the potatoes, peel them and crush them with a fork with 70 g butter, warm milk and a pinch of grated nutmeg.
Taste this puree (which must remain a little liquid to spread well) and salt if necessary.

Preheat the oven to 200 °C (390 °F).
In a buttered casserole, put one layer of mashed potatoes, then the meat, then the remaining mashed potatoes.
Sprinkle with breadcrumbs and add some butter chips.
Bake until the gratin is golden brown (finish possibly with the grill while watching well).

This dish is sometimes nicknamed "pâté des gueux" (beggars's pâté), since made with the meat leftovers of the week. Beef can be replaced by veal, pork, lamb… It refers to Antoine Parmentier who contributed to make potatoes widespread in France.
You can replace pot au feu beef with ground beef. In that case cook it with the onion for 15 min (stirring from time to time), before adding the stock.
Replace potatoes with pasta sheets and "Hachis Parmentier" becomes "Lasagna". Make your breadcrumbs yourself (just crush some old hard bread).