Place all of the meatball ingredients into a large mixing bowl. Use your hands to mix everything up until the meat mixture is well blended.
Because you want the meatballs to be smaller than regular meatballs, scoop the mixture up with a small spoon or a melon baller (that's what I like to use as it's the perfect size) and gently roll the mixture in your hands to form a meatball. Set the meatball onto a baking sheet covered with parchment and repeat until you've used up all the meat. You should end up with 34 meatballs, give or take. Tip: Rub some olive oil into your palms—it makes handling the mixture much easier as the mixture is a little tacky (which is normal).
Heat olive oil in a Dutch oven or stock pot over medium heat and when the oil is hot, lower the heat to medium-low and transfer a few meatballs into the pot (don't overcrowd them). Cook them for 30 seconds to a minute or until they're lightly browned, then flip them over with tongs and cook for another 30 seconds to a minute. Transfer them to the baking sheet and continue until all of the meatballs are cooked; set aside.
Add a smidge more olive oil to the pot. Add the onions, carrots, and celery, and season with just a bit of salt. Sauté until the veggies have softened, then stir in the garlic and chili peppers; sautée for 30 seconds.
Add the meatballs back to the pot. Poor the chicken broth into the pot, then stir in the spinach. Finally, pop the parmesan rind into the pot. Bring everything to a rolling boil, then decrease to a low simmer for 15 minutes or until the meatballs are cooked, registering an internal temperature of 160º F.
While the soup simmers, cook your acini de pepe as per the directions on the package. When done, add the pasta to the soup. Another option is you can spoon it into bowls and ladle the soup over top.
Garnish each bowl with some freshly shaved parmesan and a spritz of lemon juice! (Optional, but highly recommended!)