Preheat oven to 375 degrees F (190 degrees C). Spray the inside of a 9x13-inch baking dish.
Using a spoon, remove seeds and pulp and discard. Grease a 3 quart microwave casserole dish. Uncover and allow to sit about 5 minutes before serving. Microwave on high until no longer pink (about 4 minutes); stirring once. Place 1/4 cup water in the bottom of a small casserole dish. This spaghetti pie recipe pulls together all of the best aspects of a comforting Italian classic – pasta – cheese, a zesty meat sauce, and more cheese!
Drain; stir to break meat into smaller pieces.
Add tomato sauce, water, mushrooms, remaining seasonings and spaghetti. Spaghetti pie is the perfect dish for a kid friendly weeknight dinner or to serve to a group of hungry guests. Place in the microwave 3-4 minutes (do not cook longer than 5 minutes whole). Remove the squash from the microwave and slice from top to bottom lengthwise. Microwave at 75% power for 7 minutes, or until heated through. Spread the spaghetti mixture into the casserole dish. Place glass cover on the casserole dish.
Pierce spaghetti squash with a fork about 8 times. Sprinkle with shredded Romano cheese. Spread the spaghetti sauce over the spaghetti mixture.
Cover with casserole lid; microwave for 10-12 minutes or until spaghetti is tender, stirring twice.
Place spaghetti squash cut side down on a baking sheet and bake for 20-25 minutes or until the skin of the squash gives when you press on it. Once squash is done cooking, remove threads and place in a greased 8x8 baking dish. Then reduce oven heat to 350 degrees.