Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper.

In a large mixing bowl, combine the ground beef, ground pork, breadcrumbs, Parmesan cheese, parsley, beaten egg, 2 cloves of minced garlic, salt, and pepper. Use your hands to gently mix until just combined. Be careful not to overmix, as this can make the meatballs tough.

Roll the mixture into small meatballs, about 1/2 to 3/4-inch in diameter. You should get about 40-50 small meatballs. Place them in a single layer on the prepared baking sheet.

Bake for 15-18 minutes, or until they are browned and cooked through. Set aside.

While the meatballs are baking, heat the olive oil in a large pot or Dutch oven over medium heat. Add the chopped onion, carrots, and celery (the mirepoix). Sauté for 6-8 minutes, stirring occasionally, until the vegetables are softened.

Add the remaining 2 cloves of minced garlic and cook for another minute until fragrant.

Pour in the chicken broth, increase the heat to high, and bring the soup to a boil. Once boiling, reduce the heat to a simmer.

Stir in the acini di pepe pasta and cook according to package directions, usually about 8-10 minutes, or until al dente.

Once the pasta is cooked, stir in the chopped escarole. It will look like a lot at first, but it will wilt down into the soup within 2-3 minutes.

Gently add the cooked meatballs to the soup. Let them simmer in the soup for a few minutes to absorb the flavors. Taste and adjust seasoning with salt and pepper if needed.

Ladle the hot soup into bowls. Serve immediately, topped with a generous sprinkle of extra grated Parmesan cheese and fresh parsley.