Sweet Potatoes Au Gratin

Parboil about 6 medium-sized sweet potatoes.  Cut in thick slices.  Put a layer in a well greased baking dish.  Sprinkle with salt, pepper, and 1 tablespoon brown sugar.  Repeat until the dish is filled.  Pour over the top 3/4 cup cream or rich milk and cover the top with buttered crumbs.  Bake 1/2 hour in a moderately hot oven.