In a large mixing bowl, combine the ground beef, ground pork, panko, egg yolks, chopped green onions, fresh parsley, allspice, nutmeg, salt, and pepper. Mix until fully incorporated.

Divide the mixture into 24 equal portions and roll them into meatballs about 1 to 1.25 inches in diameter.

Heat olive oil in a Dutch oven over medium-high heat. Brown the meatballs on all sides for 2-3 minutes. Remove and set aside.

In a pot, bring salted water to a boil. Cook elbow macaroni according to package instructions for 7-8 minutes until al dente. Drain and set aside.

Lower heat and melt butter in the same Dutch oven. Whisk in flour and stir for 1-2 minutes. Gradually whisk in beef stock and cook until thickened, about 3-5 minutes.

Reintroduce the meatballs to the sauce and heat through for about 5 minutes.

Stir in cooked elbow macaroni and sour cream, heating for another 2-3 minutes. Adjust seasoning as needed.

Serve immediately, garnished with fresh parsley, if desired.