Make the meatballs: In a mixing bowl combine the meat, half the cheese, the croutons, parsley, salt, pepper, egg, and ½ cup of minced onion. Mix well with your hands and divide into 24 little meatballs.

In a dutch oven or other large, heavy pot, heat 1 tablespoon of the olive oil over medium-high heat. When it’s hot, add the meatballs—half at a time—and sauté until they’re golden brown all over. Remove the meatballs to a plate.

Add the remaining olive oil to the pot along with the additional ¼ cup of onion and cook over low heat, stirring frequently, until the onion is soft. Add the garlic and cook for another couple of minutes. Stir in the escarole, cover, and cook until it’s wilted, about 3 minutes.

Add the broth and the meatballs, bring to a boil, then simmer uncovered for about 3 minutes. Serve in warm soup plates, sprinkled with the remaining Parmesan and pepper flakes.