Make the meatballs: combine all the meatball ingredients in large bowl until evenly combined. Do not overmix. Shape into small balls, about 1 inch or smaller.
Heat a large Dutch oven to medium heat. In batches, sear the meatballs until browned, about 5-7 minutes. Do not overcrowd, otherwise the meatballs will steam and not brown. Meatballs won’t be fully cooked at this point. Transfer meatballs to a plate and set aside.
In the same pot, add about 2 tablespoons olive oil. Saute carrots, onion, and celery until softened, about 10 minutes. Then add garlic, and saute for another minute or 2.
Add chicken broth and water, oregano, and salt and pepper to taste. Bring to a boil. Add pasta and meatballs, and bring to a boil. Simmer for about 15-18 minutes (half-covered), or until pasta is tender and meatballs are thoroughly cooked.
Add spinach and simmer for another minute. Season with more salt and pepper if needed.
Serve with some Italian bread and cheese, if desired.