Sauce: Cut 1/2 half of the mushrooms into quarters and reserve. Finely mince remaining portion.
Heat olive oil in a heavy Dutch oven over medium heat. Add onion and minced mushrooms. Cook 10 minutes or until onions are very soft, stirring frequently.
Add garlic and mushroom quarters and cook 5 minutes, stirring constantly.
Add remaining ingredients, stir and bring to a simmer. Reduce heat and simmer. Remove to heated platter and cover to keep warm while saut?ing remaining zucchini.
Add remaining olive oil as needed. Ladle sauce over pasta. Top with zucchini slices and serve. Pass extra sauce and Parmesan cheese.
Makes: 4