Combine the flour, milk, beaten eggs, and grated nutmeg in a bowl.
Using a hand mixer, beat until combined, leaving the batter a little bit lumpy.
Melt the butter in an OVENPROOF cast-iron skillet over medium heat. Once the butter has melted, pour the batter into the skillet and bake in the oven for 15-20 minutes, or until the pancake is golden brown.
Combine the brown sugar and cinnamon until it's mixed thoroughly.
Remove the German pancake from the oven, slather the top with butter, and cinnamon and sugar mixture.
Slice the German pancake and serve immediately. Enjoy.