3 lg Baking potatoes
1 1/2 tb Butter
1    Leek, thinly sliced
1 lb Mushrooms, thinly sliced
1 ts Vegetable oil
Salt and pepper to taste
1/4 c  Butter, softened and cut in
... pieces
1/2 c  Buttermilk
1/2 c  Sour cream, at room temp

Boil the potatoes until tender. Heat 1/2 T butter in a skillet and cook the
leeks for 5 – 7 minutes, until tender and golden. Set aside. In a large
skillet, over moderate heat, cook the mushrooms in the remaining tablespoon
of butter until they begin to render their juices. Turn up the heat and
continue cooking until they are almost dry. Season with salt and pepper.
Preheat the oven to 350. When the potatoes are tender, drain, peel, and
return them to the pot. Toss over low heat to dry, then put them through a
ricer into a mixer bowl. Beat in the softened butter, buttermilk, and salt
and pepper to taste. Spread half the potatoes on the bottom of a shallow
baking dish. Spread the mushrooms over the potatoes and the leeks over the
mushrooms. Spread with 1 cup of sour cream and cover with the remaining
potatoes. Bake, uncovered, for 45 minutes to 1 hour or until browned and
bubbling.