Heat oven to 350°. Spray 12×8-inch (2-quart) glass baking dish.
Pour into the baking dish and mix together:
3 15 ounce cans sweet potatoes, drained
¼ cup firmly packed light brown sugar
Slice and place on top of the yams:
¼ cup margarine or butter
Bake at 350° for 25 to 30 minutes or until potatoes are thoroughly heated.
When the timer has 5 minutes left, pour on top:
1 bag of mini marshmallows
Cook until marshmallows are browned.