Cut spaghetti squash in half length wise. Scoop out seeds and disgard. Place in 2 quart dish cut side down. Pour small amount of water in bottom of dish. Cover the whole dish with plastic wrap. Microwave on high for 6-10 minutes. Take out of microwave and remove the "spaghetti noodles" from the squash by using a fork and scraping the inside of the vegetable.Put in serving bowl.
Brown turkey burger in small skillet with red onion.
Drain mushrooms and add to burger.
Pour spaghetti sauce on top of burger mixture and stir together.Cook until the mixture is hot.