1. Preheat oven to 350*.
2. Greased and flour baking a 13 x9 pan.
3. Prepare cake mix as directed on package. Pour batter into prepared baking pan,.
4. Cut marshmallows in half crosswise and arrange in rows over batter in pan. Mix brown sugar and nuts; sprinkle over top. Bake (If marshmallows become too brown, cover cake with aluminum foil.).