In a large bowl, mix together the ground beef, ground pork, parmesan, bread crumbs, grated onion, eggs, parsley, garlic, oregano, salt, and pepper until well combined. I like to do this by hand; do not over-mix
Roll the meat mixture into 1.5 tablespoon-sized balls and place them on a plate.
In a Dutch oven over medium heat, add the olive oil once hot. Brown the meatballs on all sides in batches; you do not need to cook them all the way through. Once browned, place them back on the plate, about 15 minutes.
No need to wipe out the pan, add the additional tablespoon of olive oil, carrots, onion, and celery, and cook, stirring occasionally, until softened, about 10 minutes.
Stir in the garlic until fragrant, 30 seconds.
Add the chicken stock, scrape off any browned bits off the bottom of the pan, and bring to a boil.
Add the browned meatballs and pasta and stir to combine. Cover and cook for 10 minutes, stirring occasionally so nothing sticks to the bottom.
Stir in the spinach until wilted. Serve immediately with more parmesan on top.