Preheat the oven to 400°F. Place a 12-inch cast iron skillet in the oven to preheat as well.
In a large bowl add 2 tablespoons of the melted butter along with the eggs, milk, flour, sugar, cinnamon, vanilla and salt. Whisk vigorously until combined and the mixture is smooth.
Fold in the chopped apples.
Carefully remove the skillet from the oven and add the remaining 2 tablespoons of butter. Using a pastry brush, coat the entire bottom and sides of the pan with the butter. Pour the batter into the pan and return to the oven.
Bake until the pancake has risen and is puffed up, about 20 minutes. (Do not open the oven door during the cook time)
Remove the pan from the oven and cut the Dutch baby into slices. Serve immediately with warm maple syrup.
Notes
Try this recipe with your favorite fruit instead of apples.