Pour milk into a large mixing bowl, tear bread into small pieces and add to the milk; soak 10 minutes.
Add ground turkey, chopped green onions, minced garlic and mix together.
Scoop out with spoon and roll between wet palms to form 1/2-inch balls.
Set aside.
Soup
Heat olive oil in a pot over medium heat just until it starts to shimmer. Add onions, carrots and celery. Cook, stirring occasionally until vegetables soften, add chopped garlic and cook, stirring, 2 more minutes.
Place meatballs on top of vegetables.
Gradually pour in broth. Gently stir broth into vegetables without breaking the meatballs. Cover and cook over low heat, just barely bubbling until meatballs are cooked through.
Add kale or spinach, cover and simmer just until kale/spinach is wilted. Gently mix together and serve.