In a large bowl, combine the ground beef, ground pork, crumbled bread, chopped parsley, fresh oregano, grated parmesan, egg, salt, and pepper. Knead everything together with your hands until well mixed. Pinch off small pieces and roll them into balls.

In a large skillet over medium-high heat, heat 1 tablespoon of olive oil. Add some of the meatballs to the pan, ensuring plenty of space between them. Cook for 4-5 minutes, flipping them halfway through until browned on all sides. Remove and set aside, then repeat with the remaining meatballs.

In a large soup pot, heat another tablespoon of olive oil over medium-high. Add the diced onions, carrots, and celery, sautéing until tender. Stir in the minced garlic and cook for another 30 seconds until fragrant.

Pour the chicken broth into the pot and bring to a boil. Stir in the acini pasta and the cooked meatballs, reducing the heat to medium. Cover and cook for about 10-12 minutes until the pasta is al dente.

Stir in the chopped spinach and let it cook until wilted. Taste and season with additional salt and pepper if needed. Serve hot, preferably adorned with extra parmesan cheese.