In a large mixing bowl, combine ground beef and pork. Add bread crumbs, parsley, oregano, parmesan, egg, 1 tsp salt, and 1/4 tsp pepper.

Gently toss the mixture with your hands until evenly combined. Shape into very small meatballs, about 3/4 inch to 1 inch in diameter. Transfer to a large plate.

Heat 1 Tbsp olive oil in a large non-stick skillet over medium-high heat. Add half of the meatballs and cook until browned on 2-3 sides, about 4 minutes total. Transfer to a paper towel-lined plate.

Repeat the browning process with the remaining meatballs. Note: Meatballs will not be fully cooked through at this stage; they will finish cooking in the soup.

While browning the meatballs, heat the remaining 1 Tbsp olive oil in a large pot over medium-high heat. Add carrots, onions, and celery. Sauté until softened, about 6-8 minutes. Add garlic and sauté for 1 minute longer.

Pour in the chicken broth and season with salt and pepper to taste. Bring the mixture to a boil. Add the pasta and browned meatballs. Reduce heat to medium-low.

Cover and simmer, stirring occasionally, until the pasta is tender and the meatballs are cooked through, about 10 minutes. Stir in the spinach during the last minute of cooking.

Serve hot, sprinkled with additional parmesan cheese.