In a mixing bowl, combine ground pork and ground beef. Add breadcrumbs, egg, grated Parmesan cheese, minced garlic, salt, and black pepper. Mix lightly and form into 3/4-inch meatballs.

Heat olive oil in a large pot over medium heat. Add meatballs in batches and cook for 5-7 minutes until golden brown. Remove and set aside.

In the same pot, add diced onion, carrots, and celery. Sauté for 5-7 minutes until softened. Stir in remaining minced garlic for 30 seconds.

Pour in chicken broth, scraping up browned bits. Bring to a boil. Return meatballs and reduce heat to simmer for 10-15 minutes.

Stir in acini di pepe pasta and simmer for 8-10 minutes until tender. In the last 2-3 minutes, gently stir in chopped escarole or spinach.

Taste and adjust seasoning. Serve hot, topped with extra grated Parmesan cheese.