Step 1: Prepare the Meatballs

1. In a large mixing bowl, combine the ground beef, ground chicken, bread crumbs, grated Parmesan cheese, egg, Italian seasoning, salt, and pepper.
2. Mix the ingredients together until they are well combined but do not overwork the meat mixture, as this can make the meatballs tough.
3. Roll the mixture into small meatballs, each about 1 inch in diameter. Aim to make uniform-sized meatballs for even cooking. Set aside.

Step 2: Cook the Meatballs

1. In a large pot or Dutch oven, heat 1 tablespoon of olive oil over medium heat.
2. Once the oil is hot, carefully add the meatballs in batches. Avoid overcrowding the pot to ensure even browning.
3. Cook the meatballs for 5-7 minutes, turning occasionally, until browned on all sides. They do not need to be fully cooked at this stage, as they will finish cooking in the soup.
4. Once browned, remove the meatballs from the pot and set them aside on a plate.

Step 3: Cook the Vegetables

1. In the same pot, without cleaning it, add the finely chopped onion, sliced carrots, and sliced celery.
2. Sauté the vegetables over medium heat for about 5 minutes until softened and fragrant. Stir occasionally to prevent sticking.
3. Add the minced garlic and cook for another minute until aromatic.

Step 4: Add the Broth

1. Pour in the 8 cups of chicken broth into the pot with the sautéed vegetables. Scrape the bottom of the pot to deglaze and lift any flavorful browned bits.
2. Increase the heat and bring the soup to a gentle boil.
3. Once boiling, reduce the heat to low and let the soup simmer for about 10 minutes to allow the flavors to develop.

Step 5: Cook the Pasta

1. Add 1 cup of small pasta (like acini di pepe or orzo) to the simmering broth.
2. Stir and let the pasta cook for 6-8 minutes, or until it reaches your preferred level of tenderness.

Step 6: Return the Meatballs and Add the Greens

1. Gently return the browned meatballs to the soup.
2. Add 6 cups of roughly chopped spinach or escarole to the pot.
3. Allow the soup to simmer for an additional 5 minutes, or until the meatballs are fully cooked through and the greens are wilted.

Step 7: Garnish and Serve

1. Ladle the soup into bowls.
2. Garnish each serving with a sprinkle of freshly grated Parmesan cheese.
3. Serve warm and enjoy the rich, comforting flavors of your homemade Italian Wedding Soup!