In a mixing bowl, combine ground beef, ground pork, onion, egg, breadcrumbs, parsley, kosher salt, pepper, nutmeg and allspice until blended.
Shape into 20 meatballs.
In a large nonstick skillet melt 1 Tablespoon butter over medium heat.
Add the meatballs and cook until browned on all sides, stirring occasionally.
Transfer the meatballs to a dish and reserve.
In the same skillet melt the remaining 2 Tablespoons butter over medium heat.
Add flour and cook until blended and lightly browned, stirring frequently.
Whisk in broth and Worcestershire sauce.
Bring to a boil over medium-high heat.
Reduce heat to medium and return the reserved meatballs to the skillet.
Simmer, covered, until the meatballs are cooked through, about 15 minutes.
Stir in heavy cream and, if desired, sprinkle with additional chopped parsley.