In a large bowl, stir together the carrots, onions, and drained spinach. Add the scallions (green onions) and garlic. Stir until combined. Add the sour cream, mayonnaise, Worcestershire sauce, and gluten-free soy sauce. Stir. If desired, add the Parmesan cheese. Serve. Store leftover dip in the refrigerator for up to three days.