In a small bowl, mix breadcrumbs and milk. Rest 5 minutes.
In a large bowl, combine beef, pork, onion, garlic, soaked breadcrumbs, egg, allspice, nutmeg, salt, and pepper. Mix just until combined.
Roll into 1 ½-inch meatballs (about 20–24).
Melt 2 tbsp butter in a large skillet over medium heat. Brown meatballs in batches, 5–7 minutes, then transfer to a plate.
In the same skillet, melt 3 tbsp butter. Whisk in flour and cook 2 minutes.
Slowly whisk in beef broth. Add Worcestershire and Dijon. Simmer until slightly thickened.
Reduce heat to low. Whisk in sour cream until smooth (do not boil). Season with salt and pepper as needed.
Return meatballs to the skillet. Cover and simmer 10–12 minutes until cooked through.
Cook egg noodles according to package directions. Drain and toss with 2 tbsp butter.
Serve meatballs and gravy over buttered noodles. Garnish with parsley if desired.