Yam Casserole

10 to 12 small yams, size of large potatoes
1/2 C brown sugar
1 tsp salt
1/2 tsp pepper
4 T butter, cubed small
1/2 to 1 C walnuts or pecans
1 small bag miniature marshmallows

Peel and slice yams into 1/2-inch discs. Arrange half the yam slices in a glass baking dish. Mix sugar, salt, and pepper, then sprinkle half of it on the yams. Dot with half the butter. Arrange the remaining yams and top with the rest of the sugar and butter. Cover with aluminum foil and bake at 400 degrees for 30 min. Sprinkle with nuts, cover and continue baking another 45 minutes or until yams are soft. Five minutes before serving, remove foil, cover with mini marshmallows and bake uncovered until golden. Serves 12.