1. Make the Filling:

   • In a large saucepan, melt the butter over medium heat. Add the chopped onion and sauté until soft and translucent, about 5 minutes.
   • Stir in the flour to form a roux, cooking for 1-2 minutes until it’s lightly golden.
   • Gradually add the beef broth while whisking to prevent lumps. Continue stirring until the mixture thickens (about 5-7 minutes).
   • Add the shredded beef, Worcestershire sauce, salt, pepper, and nutmeg (if using). Stir to combine and cook for another 2-3 minutes.
   • Transfer the mixture to a bowl, cover with plastic wrap, and let it cool. Once cooled, refrigerate for at least 2 hours (or until firm).

2. Shape the Bitterballen:

   • Once the filling is chilled and firm, use your hands to shape small balls (about 3-4 cm or 1-1.5 inches in diameter).

3. Prepare for Breading:

   • Set up a breading station: Place the breadcrumbs in one bowl and beat the eggs in another.

4. Bread the Balls:

   • Dip each ball into the beaten eggs, letting any excess drip off. Then roll in the breadcrumbs until fully coated. For extra crunch, you can dip the balls in the eggs and breadcrumbs again for a double coat.

5. Fry the Bitterballen:

   • In a deep pan or fryer, heat oil to 180°C (350°F). Carefully add the bitterballen in batches, frying them until golden brown and crispy, about 3-4 minutes.
   • Use a slotted spoon to remove them from the oil and place them on paper towels to drain excess oil.

6. Serve:

   • Serve the bitterballen hot with a side of mustard for dipping.

Tips:

• If you want to make a larger batch, you can freeze uncooked bitterballen. Just fry them straight from the freezer; they may take an extra minute or two.
• Experiment with different seasonings or add herbs to the filling for extra flavor.