In a large bowl, mix breadcrumbs and milk. Let sit for a few minutes until absorbed.
Add ground beef, ground pork, egg, allspice, nutmeg, garlic powder, onion powder, salt, and pepper. Mix until just combined.
Shape into 1-inch meatballs.
In a large skillet over medium heat, heat olive oil and cook the meatballs until browned and cooked through. Remove and set aside.
In the same skillet, melt butter. Whisk in flour and cook for 1 minute.
Gradually whisk in beef broth, heavy cream, Worcestershire sauce, and Dijon mustard. Simmer until thickened.
Return meatballs to the skillet and simmer in the sauce for a few more minutes.
Serve warm with mashed potatoes or egg noodles.