Combine beef, breadcrumbs, Parmesan cheese, egg, salt, and pepper; shape into meatballs 1 inch in size.

In a skillet, cook the meatballs for 2 to 3 minutes on each side.

Add the broth, carrot, celery, onion, and garlic to the slow cooker.

Drop browned meatballs into slow cooker.

Cook on low for 4 hours.

Add orzo and spinach, and cook on high for 20-25 minutes until the orzo is cooked.

Taste for seasoning before adding salt and/or pepper to the dish.