Making Italian Meatball Soup is simple and enjoyable. Follow these steps for success:

1. Preheat the Oven: Begin by preheating your oven to 400°F (200°C). This is for browning the meatballs for added flavor.
2. Make the Meatballs: In a bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, garlic, oregano, salt, and pepper. Mix until well combined.
3. Form the Meatballs: Shape the mixture into small meatballs, approximately 1 inch in diameter. Place them on a baking sheet lined with parchment paper.
4. Bake the Meatballs: Bake the meatballs in the preheated oven for 20 minutes or until they are browned and cooked through.
5. Prepare the Soup Base: In a large pot, heat a bit of oil over medium heat. Sauté the diced onion, carrots, and celery until they are softened, about 5-7 minutes.
6. Add the Broth and Tomatoes: Pour in the chicken or vegetable broth and add the canned tomatoes with their juices. Bring the mixture to a simmer.
7. Add the Meatballs: Once the broth is simmering, carefully add the baked meatballs to the pot. Let them simmer in the broth for about 15 minutes.
8. Stir in the Greens: Just before serving, stir in the chopped spinach or kale. Cook for an additional 2-3 minutes until the greens are wilted.
9. Taste and Adjust: Taste the soup and adjust seasoning if necessary. You can add more salt, pepper, or herbs based on your preference.
10. Serve Hot: Ladle the soup into bowls and garnish with fresh basil if desired. Enjoy your delicious Italian Meatball Soup!