Spaghetti Squash with Turkey Meatballs

Name: Spaghetti Squash with Turkey Meatballs
Ingredients: 1 spaghetti squash (about 3 pounds), halved lengthwise; Coarse salt and freshly ground pepper; 1 tablespoon plus 1 teaspoon extra-virgin olive oil; 1 onion, finely chopped; 2 garlic cloves, minced; 1 ½ teaspoons chopped fresh oregano; ½ ounce grated Parmesan cheese (3 tablespoons); 1 tablespoon dried breadcrumbs; 8 ounces lean ground turkey; 8 ounces mixed mushrooms, such as shiitake, cremini, and oyster, cut ¼ inch thick (about 3 cups); 1 cup homemade or store-bought low-sodium chicken stock; 4 ounces baby spinach (about 5 cups), washed well