Slice the squash in half lengthwise and scoop out the seeds. Place squash, cut side down, in a baking dish. Add water and cover tightly with foil. Bake at 375° for 20-30 minutes or until easily pierced with a fork.
Meanwhile, melt butter in skillet. Add the onion, garlic, mushrooms, herbs and seasonings; sauté until onion is transparent. Add the tomatoes; cook until most of the liquid has evaporated. Set aside.
Scoop out the squash, separating strands with a fork.
Combine squash, tomato mixture and all remaining ingredients except Parmesan cheese. Pour into a greased 2-qt. casserole. Sprinkle with Parmesan cheese.
Bake, uncovered at 375° for 40 minutes or until heated through and top is golden brown.