Preheat the oven to 425°F.
Peel, core and chop one apple and place it in a bowl along with the cinnamon, brown sugar and 1 tablespoon of melted butter. Stir to combine then set aside.
In a separate bowl, mix the flour, sugar and salt together.
In another bowl, whisk together the milk, eggs and vanilla. Add the wet ingredients to the dry ingredients and whisk the batter until smooth.
Melt the remaining two tablespoons of butter in a 10-inch cast iron skillet. Swirl the butter to coat the bottom and sides of the skillet.
Pour the batter into the skillet then scatter the apples overtop. Bake the Dutch Baby for 15 minutes or until puffed up and golden brown.
Sprinkle the Apple and Cinnamon Dutch Baby with ¼ cup of powdered sugar and serve immediately. Enjoy!