Combine the mushrooms, olive oil, vinegar, garlic, basil and Italian seasoning in a resealable plastic bag and refrigerate for 4 hours.
Preheat oven to 350 degrees F.
Place the mushrooms in a 2 to 3-quart baking dish, cap-side-down. Top the mushrooms with the sliced tomatoes and sprinkle the shredded mozzarella evenly over top. Bake for 40 minutes, or until browned and bubbling. Remove from the oven and sprinkle with shredded Parmesan cheese and fresh parsley. Serve with sliced baguettes or crusty bread.