In a large bowl combine the ground beef, breadcrumbs, egg, salt, pepper, nutmeg, and allspice together until thoroughly mixed. Shape ingredients into meatballs that are 1 to 1 1/4-inch in diameter.
In a large skillet heat 1 tablespoon of butter and 1 tablespoon of oil over medium-high heat. Add the prepared meatballs and cook for 9 minutes, turning occasionally to ensure even browning. You can use a wooden spoon to move them around. Remove the meatballs and set them aside.
Add the remaining 3 tablespoons of butter to the skillet. Sprinkle in the flour and whisk for 1 to 2 minutes, or until the mixture turns golden brown.
Add the garlic powder and Worcestershire sauce and stir. Slowly pour in the beef broth, whisking continuously.
Set the heat to medium and whisk in the sour cream and dijon mustard. Allow the sauce to come to a simmer and continue cooking for 8 to 10 minutes or until the sauce begins to thicken.
With 5 minutes left in the sauce simmering add the meatballs back to the skillet. While the sauce and meatballs are simmering cook the egg noodles in boiling water until al dente and drain. Serve with meatballs and sauce.
If you don’t have a big enough skillet to hold them all just work in 2 batches and add a tablespoon of butter each time you add a new set of meatballs. Avoid overcrowding them.