1. Preheat oven to 350°F (175°C).

2. Place cast iron skillet over medium heat and melt the butter, swirling to coat the pan.

3. Stir in brown sugar and granulated sugar until the mixture bubbles and forms a smooth caramel.

4. Add sliced apples, cinnamon, and nutmeg, tossing to coat and cook for 5 to 7 minutes until apples are slightly tender.

5. Remove skillet from heat and let cool briefly while you prepare the topping.

6. In a bowl whisk together flour, baking powder, and salt.

7. In another bowl beat eggs, then stir in milk, vanilla extract, and melted oil until combined.

8. Gently fold wet ingredients into dry ingredients until a thick batter forms.

9. Spoon or dollop the batter evenly over the caramelized apples in the skillet, leaving small gaps for fruit to peek through.

10. Bake in preheated oven for 25 to 30 minutes until topping is golden brown and a toothpick inserted into the center comes out clean.

11. Let skillet rest for 5 to 10 minutes before serving to thicken the caramel base.

12. Serve warm topped with powdered sugar, whipped cream, or vanilla ice cream.