Place a 9-inch nonstick fry pan on the middle rack of the oven and preheat to 425 degrees.
In a small bowl, combine the flour, salt, pepper and nutmeg.
In a large measuring cup, beat eggs until foamy. Gradually whisk in the milk. Add flour mixture and whisk until smooth.
Once oven is preheated, carefully remove fry pan from the oven. Add butter and swirl to coat the bottom and sides. Moving quickly, pour batter into the prepared pan and place pan back in oven.
Bake for 18-20 minutes or until puffed and golden. Do not open the oven door while Dutch baby is baking.
Remove pan from the oven and pile on the toppings. Serve immediately.
Notes
To make quick pickled red onions, peel and thinly slice 1 red onion and place in a small jar with a lid. Fill with enough white vinegar to cover by ½ inch. Let sit at room temperature for 1 hour. Transfer to the refrigerator to chill until ready to use.
Recipe by Two of a Kind at http://www.twoofakindcooks.com/deli-sandwich-dutch-baby/