Place bread in a single layer on ungreased baking sheets; brush with butter. In a small bowl, mix sugar and cinnamon; sprinkle over tops. Bake at 400 for 2-3 minutes or until lightly browned.
Meanwhile, in another bowl, mix the sweet potatoes, pecans, brown sugar and butter. Spoon onto toasts; top with marshmallows, pressing lightly to adhere. Broil 3-4 inches from the heat for 1-2 minutes or until marshmallows are lightly browned.