Combine eggs, milk, flour, lemon zest, salt, and maple syrup in a blender. Pulse until combined.
On the stop top, melt 1 tablespoon butter in a 10" cast iron (well seasoned) skillet. Swirl around to cover the pan once melted. Remove from heat and pour in batter. Bake in oven until golden brown and puffed, 20-25 minutes.
Dice apples in to 1/2" chunks. Place in a pot with maple syrup, cinnamon, and nutmeg. Heat oven medium-low heat until apple are cooked, 10-15 minutes.
Remove dutch baby from oven and top with apples. Serve with butter and extra maple syrup if desired.