Ginger-chicken meatballs with chinese broccoli

Cutlets and meatballs

1 garlic clove, finely grated 1 lb ground chicken 1 tablespoon reduced-sodium soy sauce 2 teaspoons finely grated ginger 4 scallions, thinly sliced, plus more for serving 2 cups low-sodium chicken broth, divided 2 tablespoons vegetable oil ½ bunch Chinese broccoli, chopped ½ teaspoon crushed red pepper flakes Kosher salt, freshly ground pepper