Bring broth to a simmer in a Dutch oven (do not boil). Keep warm over low heat.
Soak the bread in milk for 5 minutes, and squeeze moisture from the bread. Combine the bread, beef, minced onion, 1/4 cup cheese, 1/4 cup parsley, salt, and pepper in a bowl. Shape mixture into 24 (1 1/2-inch) meatballs. Add meatballs and carrot to broth, and bring to a boil. Reduce heat, and simmer 8 minutes. Stir in orzo, and cook 2 minutes. Sprinkle with 1/4 cup cheese and 1/4 cup plus 2 tablespoons parsley.