Florentine Meatballs

Name: Florentine Meatballs
Ingredients: 1 box frozen spinach, defrosted in the microwave; 1 1/3 pound (1 package) ground turkey breast; 1 medium onion, finely chopped, divided; 3 cloves garlic, chopped; 1 large egg; 1 3/4 cups milk, divided; 3/4 cup bread crumbs, 3 handfuls; 1/2 cup grated Parmigiano-Reggiano, 2 palm fulls; Coarse salt and black pepper; Extra-virgin olive oil, for drizzling; 2 tablespoons butter; 2 tablespoons all-purpose flour; 1 cup chicken stock; 1 (10-ounce) sack shredded provolone or blend of Italian cheeses, available on dairy aisle; 1/2 teaspoon freshly grated nutmeg, eyeball it; 1/4 cup parsley leaves, chopped