My dad tipped me off ahead of time to make this cake for them, and to be honest I was a little nervous. Last time I made an upside down cake it stuck to the pan and I had to patch it back together! I used a highly reviewed Dunkin Hines recipe, with a few alterations to cut back on fat, calories, and sugar.
Topping:
1/4 cup butter
1/2 cup brown sugar
20 oz can of pineapple rings
cherries or walnuts, optional
Cake:
Dunkin Hines Pineapple Supreme cake mix
1 pkg vanilla instant pudding (I used fat free, sugar free)
4 eggs
1 cup water (I used the 100% pineapple juice from the can)
1/2 cup oil
Preheat oven to 350°. Generously grease a 12" baking pan.
Melt butter for the topping in a medium bowl in the microwave. Stir in the brown sugar until dissolved. Spread into the bottom of the baking pan and arrange the pineapple rings, cherries, and/or walnuts, if using.
Combine the cake mix, pudding mix, eggs, water (or juice), and oil in a mixing bowl. Mix at medium speed until combined, about 2 minutes. Pour batter over the pineapple rings. (Note: All of the batter may not fit in the pan. Make a smaller cake alongside, or reserve for later use.)
Bake for 1 hour, or until toothpick comes out clean. Let cool a few minutes, then invert onto serving plate while still warm.

I was so excited it popped out of the pan cleanly! The cake itself was really moist and rich. I've heard people boasting about including instant pudding in cake mix before, but never tried it myself.
And my will power is happy to report we sent the leftover half of the cake home with Jack and Sylvia!