How to Make It
Combine the bread, onion, parsley, and garlic in a food processor; pulse until finely chopped. Transfer to a medium bowl, add the milk and Worcestershire, and let stand for 5 minutes.
Add the beef, eggs, 1 tablespoon salt, and 1 teaspoon pepper and gently combine. Form into 40 meatballs (about 2 tablespoons each).
To cook immediately: Place the meatballs on foil-lined broilerproof baking sheet(s) and broil, one sheet at a time, turning once, until cooked through, 8 to10 minutes.
To freeze and cook later: Freeze the uncooked meatballs on wax paper–lined baking sheet(s) until firm, transfer to a freezer bag, and freeze for up to 3 months. To cook, broil the frozen meatballs as above, adding 2 to 4 minutes to the cooking time.