Heat 12" cast iron skillet on stovetop over medium heat. Melt butter and coat bottom of pan. Remove from heat.
Sprinkle brown sugar evenly over melted butter.
Layer whole pineapple slices over bottom of pan. Line walls of pan with ½ slices. Place a cherry in the center of each ring and half-ring.
To mix batter, do NOT follow instructions on box. Instead, combine cake mix, pineapple juice, oil, and eggs in a large bowl. Mix with hand mixer until moistened, then beat for two minutes until smooth.
Pour batter carefully over fruit.
Bake 40-45 minutes or until cake is golden brown and springs back when touched lightly in center. A toothpick inserted between fruit and into cake should come out clean
Remove from oven and let cool ten minutes. Run a knife around perimeter of cake to loosen. Place a cake platter upside down over skillet. Place a cutting board over plate, then carefully turn everything over. Remove skillet. If needed, replace displaced fruit.
Tip: Have extra fruit on hand so you can adjust placement based on the size of the rings.
Recipe by Culinary Musings at http://www.culinarymusings.com/2021/04/cast-iron-pineapple-upside-down-cake/