In a large nonstick skillet, heat olive oil over medium heat and add onions and garlic. Sauté until translucent, about 4-5 minutes. Add celery and parsley and cook until soft, about 3-4 minutes. Remove from heat and cool.

In a large bowl, combine ground turkey, ground beef, egg, cooked onion mixture, breadcrumbs, salt, pepper, and allspice. Mix well and form into 16 meatballs.

Add beef broth to the skillet and bring to a boil. Reduce heat to medium-low and gently add meatballs. Cover and simmer for about 20 minutes, until cooked through.

Remove meatballs with a slotted spoon and set aside in a serving dish. Strain broth, transfer to a blender with cream cheese, and blend until smooth. Return sauce to skillet, add meatballs, and simmer for a few more minutes.