Preheat the oven to 350 degrees F (175 degrees C).

Melt butter in a 9-inch cast iron skillet over medium heat. Stir in brown sugar; heat until bubbly. Remove from heat. Arrange pineapple rings and pecans on top.

Sift flour, baking powder, and salt together in a bowl; repeat sifting twice more.

Beat white sugar and eggs together in a bowl with an electric mixer until light and fluffy.

Alternate folding flour mixture and pineapple juice into egg mixture in 3 batches, beginning and ending with flour mixture. Pour over pineapple slices.

Bake in the preheated oven until a toothpick inserted into center comes out clean, 30 to 35 minutes. Let cool in the skillet for 5 minutes. Invert carefully onto a serving platter.