Heat oven to 350°F (325°F for dark or nonstick pan).
In 13x9-inch pan, melt butter in oven.
Sprinkle brown sugar evenly over butter.
Arrange pineapple slices on brown sugar, next place a cherry in center of each pineapple slice, and arrange remaining cherries around slices; press gently into brown sugar.
Add enough water to reserved pineapple juice to measure 1 cup.
Make cake batter as directed on box, substituting pineapple juice mixture for the water.
Pour batter over pineapple and cherries.
Bake 40-50 minutes or until toothpick inserted in center comes out clean.
Immediately run knife around side of pan to loosen cake.
Place heatproof serving plate upside down onto pan; turn plate and pan over.
Leave pan over cake 5 minutes so brown sugar topping can drizzle over cake; remove pan. Cool 30 minutes.
Serve warm or cool.
Store covered in refrigerator.