Melt butter in 9-inch cast iron skillet. Add brown sugar until melted.
1/4 cup butter, 1 cup brown sugar
Drain pineapple, reserve ⅓ of the juice. Set aside.
1 15.25 oz. can pineapple slices
Arrange pineapple slices and cherries over brown sugar mixture. You should get 7 rings on the bottom. Cut the remaining pineapple rings in half and arrange along the side of the skillet spacing in between the round rings (see photo). Set aside.
maraschino cherries
Beat egg yolks with hand or stand mixer with whisk attachment until thick. Gradually add the sugar and mix well.
3 eggs, 1 cup sugar
In separate bowl combine flour, baking powder, salt and add to the egg mixture.
1 cup all-purpose flour , 1 teaspoon baking powder, 1/2 teaspoon salt
Stir in pineapple juice.
Beat egg whites until stiff and fold into batter. Spoon over pineapples evenly.
Bake at 350 for 40 - 45 minutes. (Check sooner to see if it's done. It can tend to bake fast.)
Cool in skillet for 30 minutes, then invert onto serving plate.