Barbara's Lean Lasagna

Ingredients

• ["1 lb ground round (increase to 2 lb if you like it meaty) or 1 lb ground turkey (increase to 2 lb if you like it meaty)", "1 medium onion, chopped (optional)", "1 cup sliced mushrooms (optional)", "3 cups spaghetti sauce, divided", "2 cups fat-free ricotta cheese", "2 cups shredded part-skim mozzarella cheese", "1 teaspoon garlic powder (or to taste)", "1 tablespoon oregano (or to taste)", "1 tablespoon basil (or to taste)", "6 -8 zucchini, thinly sliced lengthwise (these are your \"noodles\"")""