Step 1: Prepare the Meatballs

1. In a large mixing bowl, combine ground chicken, breadcrumbs, Parmesan cheese, beaten egg, minced garlic, chopped fresh basil, salt, black pepper, and Italian seasoning.
2. Mix well until all ingredients are evenly incorporated.
3. Roll the mixture into small meatballs, about 1-inch in diameter.
4. Heat a drizzle of olive oil in a large pot over medium heat and sear the meatballs until golden brown on all sides. Remove and set aside.

Step 2: Prepare the Soup Base

1. In the same pot, add a bit more olive oil and sauté chopped onions until soft and translucent.
2. Stir in minced garlic and red pepper flakes, cooking for about 30 seconds until fragrant.
3. Pour in the crushed tomatoes and chicken broth, stirring to combine.
4. Season with salt, black pepper, and additional Italian seasoning to taste.
5. Let the soup simmer for about 10-15 minutes, allowing the flavors to meld together.

Step 3: Simmer the Meatballs

1. Return the seared meatballs to the pot, submerging them in the tomato broth.
2. Cover and simmer for another 10-15 minutes, ensuring the meatballs are cooked through.
3. If using pasta, add it to the soup and cook until tender.

Step 4: Finish and Serve

1. Stir in shredded mozzarella cheese, allowing it to melt into the soup.
2. Garnish with fresh parsley and additional Parmesan cheese before serving.
3. Serve hot with crusty bread for dipping.