To a large skillet over medium heat, add a tablespoon of olive oil. Add the chopped onion and cook until soft and translucent; about 3 minutes.

In a large mixing bowl and with a wooden spoon or clean hands, combine ground beef, ground pork, eggs, breadcrumbs, cooked onion, salt, pepper and allspice. Mix just until combined.

Shape into meatballs with your hands, using a regular cookie scoop for small meatballs, or an ice cream scoop for large meatballs.

To make the gravy, add ¼ cup butter to the skillet to melt. Whisk in flour and cook until golden; about 2 minutes. Gradually add beef broth, Worcestershire, and half and half, whisking constantly, until thickened.

Stir in sour cream and season with salt and pepper to taste.

Add meatballs back to the skillet to ensure they are heated through. Garnish with chopped parsley and serve immediately with mashed potatoes or egg noodles on the side.