Berry Yam Bake

Peel sweet potatoes, cut into chunks; cook in water on stovetop just until fork tender (do not over cook). Save cooking water.
In a small bowl, combine flour, brown sugar, oatmeal, and cinnamon. Cut in butter as for pastry; blend until crumbly. In a 2-qt. casserole, layer half the sweet potatoes (lift out of water with slotted spoon), half the cranberries and half the crumb mixture. Repeat with remaining ingredients, ending with crumbs. Pour about 1/2 c. of the cooking water over the top. Bake at 350 degrees for 35 minutes or until cranberries are soft. Place a ring of marshmallows around the outer edge of casserole and return to oven just until marshmallows are puffed and lightly browned.
Serves 8.