Prepare the Meatballs:
In a bowl, combine ground beef, pork, breadcrumbs, Parmesan, egg, garlic, oregano, salt, and black pepper.
Mix well and form into small 1-inch meatballs (about 30-35 meatballs).
Place them on a parchment-lined baking sheet.
Brown the Meatballs:
Heat olive oil in a large pot over medium heat.
Add meatballs in batches and cook until browned on all sides (about 3-4 minutes per batch). Transfer to a plate.
Make the Soup Base:
In the same pot, sauté onion, carrots, and celery until softened (5 minutes).
Stir in garlic and cook for 30 seconds until fragrant.
Pour in chicken broth, bring to a simmer, and add salt, black pepper, and red pepper flakes.
Add Pasta And Meatballs:
Add acini di pepe (or orzo) and return meatballs to the pot. Simmer for 10-12 minutes, until pasta is tender.
Finish And Serve:
Stir in spinach and cook for 2 minutes until wilted.
Taste and adjust seasoning if needed.
Serve hot, topped with grated Parmesan and fresh parsley.