Melt butter in large, heavy pot. (As always, a Dutch oven is good.) Cook onions, leek, carrots and celery over low heat until soft, about 15 minutes. While that is cooking, sauté ground beef with oil in a frying pan, breaking up any large pieces with a wooden spoon.
When beef has lost its red color, drain excess fat, and add to vegetables. Pour in chicken broth. Mix in tomato paste. Season with salt and pepper. Stir to combine, and turn into a baking dish.
Bake in preheated 350° F oven for 10 minutes.
Put potatoes through a ricer or a food mill. Stir in milk, butter and grated nutmeg.
Take pie from oven and stir in peas. Spread the mashed potatoes on top, forming swirls with a fork. Dot with diced butter bits and return to the oven for another 30 minutes.

He Said...	She Said...
Redifines comfort food. This classic Irish dish is perfect for a cold rainy day. Can't imagine why the Irish would have great foods for when it's cold and dreary outside.	I'm abused and neglected, he has not made this for me yet.