I found several recipes online for this cake. All of the recipes looked delicious. This is my version after reviewing several of those recipes. My husband likes recipes with cake mixes & he really liked this one.
Preheat oven to 350 degrees. Spray 13x9" cake pan with cooking spray with flour. Melt butter in microwave about 30 seconds or until melted. Stir in brown sugar. Pour mixture in prepared cake pan. Spread drained pineapple on brown sugar mixture. If desired, arrange maraschino cherries on top of pineapple. If using cherry halves, place cut side up.
Combine reserved pineapple juice with enough milk to make 1 cup liquid. In large mixing bowl, combine milk mixture with cake mix, oil, sugar and eggs. With electric mixer on low speed, beat about 30 seconds or just until ingredients are moistened. Scrape sides of bowl. With mixer on medium speed, continue beating another 2 minutes. Pour batter over pineapple. Bake 55-60 minutes. (In my oven, it took 60 minutes).
Remove from oven. After 3 minutes, loosen sides of cake with a knife. Invert cake on cookie sheet or large platter. Cool. Store covered in refrigerator. Before serving, top with sweetened whipped cream or Cool Whip, if desired.