Combine ground beef, pork, egg, breadcrumbs, Parmesan, garlic, oregano, parsley, nutmeg, paprika, salt and pepper in a medium bowl. Use a teaspoon to measure out meat for even sized meatballs. With damp hands, shape them into balls. Cover and refrigerate until ready to cook.
Melt the butter in a large soup pot over medium heat. Add garlic, onion, carrot, salt and pepper and cook until translucent and fragrant, about 4 minutes. Stir in chicken broth, water and tomatoes. Cover and cook 10 minutes over medium heat or until soup comes to a boil.
Add meatballs and orzo to the boiling soup and stir to make sure they are fully submerged. Cover and simmer for another 15 minutes over medium heat. Stir in kale. Test a meatball and a piece of orzo to ensure that they are fully cooked. Taste and adjust seasoning. Serve immediately.