In a large bowl, combine beef, pork, breadcrumbs, egg, Parmesan, and half of the minced garlic to form 1-inch meatballs.
Heat olive oil in a large pot over medium heat and brown the meatballs on all sides, then remove and set aside.
In the same pot, sauté the onion, carrots, and celery until softened, approximately 5-7 minutes.
Add the remaining garlic and oregano, cooking for 1 minute until fragrant.
Pour in the beef broth and bring to a boil, then reduce heat and simmer for 15 minutes.
Add the ditalini pasta to the pot and cook according to package directions until al dente.
Return the meatballs to the pot and stir in the baby spinach until wilted.
Season with salt and pepper before serving.