• Preheat the oven to 350°F.

  Spread the shredded coconut in a 10-inch cast iron skillet and place it in the oven while it preheats. Stir once or twice until lightly toasted, about 5 to 8 minutes. Remove the skillet from the oven, transfer the toasted coconut to a bowl, and set aside.

  Add the butter and brown sugar to the same skillet and return it to the oven for 2 to 3 minutes, or until the butter has melted. Carefully stir until the butter and brown sugar are smooth and combined. Spread the chopped pineapple evenly over the caramel and sprinkle with the remaining ¼ cup chopped macadamia nuts. Set the skillet aside while you prepare the batter.

  In a medium bowl, whisk together the cake flour, baking powder, baking soda, and kosher salt.

  In a large bowl, whisk together the cane sugar, brown sugar, melted coconut oil, eggs, vanilla, mashed bananas, and sour cream until smooth.

  Add the dry ingredients to the banana mixture and stir just until almost combined. Fold in the toasted coconut and the remaining ½ cup chopped macadamia nuts, mixing only until no streaks of flour remain.

  Spoon the batter evenly over the pineapple layer and gently spread it to the edges of the skillet.

  Bake for 55 to 65 minutes, or until the cake is golden brown and a thermometer inserted into the center registers 200 to 205°F.

  Let the cake cool in the skillet for 10 minutes. Run a thin knife around the edge, place a serving platter over the skillet, and carefully invert the cake. Allow the skillet to rest upside down for about a minute before lifting it away, giving the caramel time to settle over the cake.

Notes

• A 10-inch cast iron skillet gives the best caramelization and creates beautifully crisp edges.

  If you prefer, the coconut can be toasted on the stovetop over medium-low heat, and the butter and brown sugar can be melted together on the stovetop instead of in the oven.

  For a subtle warm spice note, stir ⅛ teaspoon ground cardamom into the dry ingredients.

  Store covered at room temperature for up to 2 days or refrigerate for up to 5 days. Bring to room temperature before serving for the best flavor.