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.alpress 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

Bake 42 to 48 minutes (44 to 53 minutes for dark or nonstick pan) 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