1Heat oven to 350°F. Grease 13x9-inch pan with shortening or cooking spray.
2In large bowl, place cake mix, brown sugar and corn syrup. Break eggs into 1-cup glass measuring cup; fill with water until it reaches 2/3 cup. Add egg mixture to bowl; beat with electric mixer on medium speed 1 minute or until combined. Spread in pan. Sprinkle marshmallows and chocolate chips over batter.
3Bake 35 to 40 minutes or until toothpick inserted in center comes out clean. Cut into 6 rows by 4 rows and enjoy!