Haet oven to 350. Spray 2- 8" round cake pans w/ cooking spray or spray a 9" x 13" pan w/ cooking spray. Sprinkle brown sugar evenly over bottom of pans. Pour butter evenly over sugar.
Arrange pineapple slices evenly in single layer in each pan. Place a cherry in center of each pineapple.
In lg bowl, beat cake mix, water, oil and eggs until combined. Evenly divide batter among pans. Bake 30 mins, or until a toothpick inserted in center comes out clean. Let cakes cool. Loosen gently w/ a knife. Invert onto 2 plates.