Preheat oven to 350 F with rack in the center of the oven.
In a 10-inch cast iron skillet, over low heat, melt the butter. Using a pastry brush coat the inside of the skillet with the melted butter. Add and brown sugar and pineapple juice, and stir until combined. Remove from heat.
Pat dry the sliced pineapple rings. Place rings in the bottom of the skillet with the sugar mixture. Place a maraschino cherry in the center of each pineapple ring.
In a medium mixing bowl, sift together flour, baking powder, and salt.
In a large mixing bowl, using a stand mixer or hand mixer, cream together butter and sugar until light and fluffy. Add eggs, 1 at a time, beating well after each addition to combine. Beat in vanilla. Add half of flour mixture and mix until just combined. Add pineapple juice and stir to combine. Add remaining flour mixture, beating until just blended.
Pour batter over pineapple and sugar mixture in cast-iron skillet. Bake in preheated oven 45 minutes or until golden and a toothpick inserted in the center comes out clean. Allow cake to stand in skillet 5 minutes. Place a plate over top of skillet and invert cake onto plate, keeping plate and skillet firmly pressed together. Serve cake just warm or at room temperature. Serves 6 to 8.