Spaghetti Squash Lasagna Boats

Name: Spaghetti Squash Lasagna Boats
Ingredients: Nonstick cooking spray, for the foil; 2 medium spaghetti squashes; 3 to 4 large handfuls baby spinach; Kosher salt and freshly ground black pepper; 1 cup (246 grams) ricotta cheese; 1 cup (80 grams) Parmigiano-Reggiano, finely grated, plus more for serving, optional; 4 cloves garlic; 2 tablespoons finely chopped fresh parsley, plus more for serving, optional; 2 tablespoons finely chopped fresh basil, plus more for serving, optional; 2 teaspoons finely chopped fresh oregano, plus more for serving, optional; Olive oil, for the pan and drizzling; 18 ounces (500 grams) lean ground beef or veggie ground; 1 yellow onion, finely diced; One 24-ounce (680-milliliter) jar tomato passata; 1/2 teaspoon crushed red pepper flakes, optional; 2 cups (230 grams) grated mozzarella