In a large bowl, mix the beef, pork, parsley, allspice, nutmeg, grated onion, salt, pepper, garlic, panko and eggs until combined. Using a tablespoon or cookie scoop, measure out the meat mixture into small balls. .In a large pan, heat 2 tablespoon of olive oil over medium-high heat. Add ½ of the meatballs and cook until browned on all sides. When all of the meatballs are browned, pour off any excess grease in the pan. Lower the heat to medium and add the butter to the pan. When the butter begins to bubble, sprinkle in the flour and cook for 1 minute. Add the beef broth to the pan a little at a time.
Whisk the gravy until the broth is all incorporated. Add the salt, pepper, lemon juice, allspice and nutmeg. Whisk a few more times. Slowly add the cream.Once the gravy begins to simmer add the meatballs back into the pan. Simmer until the gravy has thickened and the meatballs are cooked through.Serve warm over mashed potatoes or egg noodles, or on a appetizer tray on crackers as a single bite.