Preheat your oven to 425 degrees
Cut the squash in half lengthwise, scrape out the seeds, rub the inside with olive oil, and sprinkle with a little salt and pepper
Place the halves cut side down on a foil-lined pan, and roast for about 30 minutes or until the tip of a knife easily pierces the skin
When the squash has cooled enough to handle it, scoop out all of the insides into a bowl, cover, and set aside
Sauté the chicken in some olive oil in a large skillet. (You can do this while the squash is roasting.)
Once the tenders have browned on both sides and are cooked through, remove them from the pan, slice them into bite-sized pieces, and set them aside
Add a little more olive oil (if needed) to the pan the chicken was cooked in, and cook the mushrooms until they are browned and starting to soften
Add the minced garlic, the thyme, and the spinach, and stir until the garlic is fragrant and the spinach is wilted
Stir the spaghetti squash and chicken into the mixture in the pan, scraping up the browned bits from the bottom of the pan with a wooden spoon for extra flavor
Continue stirring gently over medium heat until the whole mixture is heated through
Add the parmesan cheese, divide onto two plates, and top with freshly ground pepper and coarse ground salt to taste