Preheat your oven to 400°F (200°C).

In a medium bowl, combine ground beef, Italian sausage, breadcrumbs, Parmesan cheese, parsley, egg, garlic powder, salt, and pepper. Mix until thoroughly combined.

Shape the mixture into small meatballs, about 1 inch in diameter, and place them on a baking sheet.

Bake the meatballs in the preheated oven for 15 minutes or until cooked through.

While the meatballs are baking, heat olive oil in a large pot over medium heat.

Add the diced onion, carrot, and celery to the pot. Sauté for about 5 minutes, or until the vegetables are tender.

Stir in the minced garlic and cook for an additional minute, until fragrant.

Pour in the chicken broth and bring to a boil.

Once boiling, reduce the heat and add the orzo or small pasta. Cook according to package instructions (usually about 8-10 minutes).

In the last 2 minutes of pasta cooking, add the fresh spinach or escarole, cooked meatballs, salt, and pepper to the pot. Stir to combine.

If desired, add fresh lemon juice to brighten the flavor.

Serve the soup hot with additional grated Parmesan cheese on top.