Prepare the meatballs: start out by adding all the meatball ingredients into a medium bowl. Use clean hands to combine the the ingredients until fully combined.Roll the meatball mixture into small balls (approximately 3/4 inch in size is ideal). You will likely get about 50-60 meatballs depending on the size you make them.
Cook the meatballs stovetop: heat a large skillet to medium-high heat. Add a drizzle of olive oil and when glistening, add the meatballs in batches to brown the outsides, turning once or twice for about 3-4 minutes. The meatballs do not have to be fully cooked as they can cook the rest of the way in the soup. Remove and set aside.
To broil: Line the meatballs on a parchment paper lined sheet pan. Broil on high for about 5-7 minutes or until the outside of the meatballs are browned, but not cooked through just yet. Remove from the oven and set aside.
Prepare the Soup: While the meatballs cook, add a drizzle of olive oil to a heated stock pot or dutch oven pot. Add carrots, onion and celery and sauté for about 3-4 minutes or until the onions become translucent.
Add the broth, tomatoes, Italian seasoning, garlic, salt and pepper and parmesan rind. Set heat to medium and simmer until the carrots have softened and the broth comes to a low boil. Adjust the heat as needed to medium or medium-high to keep a low boil.
Add in the meatballs, spinach and ditalini pasta. Simmer for about 10 minutes or until the pasta is al dente. Remove from heat, stir in the tomato paste and allow to cool several minutes before serving. Remove the parmesan rind before serving.