Melt the butter in a saucepan over medium heat, then whisk in the flour and cook for 2 minutes until it forms a smooth, bubbling paste without browning.

Slowly whisk in the beef broth a little at a time to prevent lumps, bringing the mixture to a gentle simmer until it thickens into a very thick, smooth gravy.

Stir in the finely minced beef, fresh parsley, and ground nutmeg, then season generously with salt and black pepper to taste.

Transfer the beef ragout to a shallow dish, cover with plastic wrap pressing directly onto the surface to prevent a skin from forming, and refrigerate for at least 3 hours until completely firm.

Once the mixture is chilled and firm, scoop out tablespoon-sized portions and roll them between your hands into smooth, even balls.

Set up a breading station with two shallow bowls: one with the beaten eggs and one with the fine breadcrumbs.

Roll each ball first in the breadcrumbs, then dip into the beaten egg, and roll in the breadcrumbs once more to ensure a thick, double-coated crust that won't burst.

Heat 2 inches of frying oil in a deep pot to 350°F (175°C), and fry the bitterballen in small batches for 3 to 4 minutes until they are deeply golden brown and crispy.

Remove the bitterballen with a slotted spoon, drain on paper towels, and serve immediately with a side of spicy brown or Dijon mustard for dipping.