Preheat oven to 425 degrees
Cut the tops and bottoms off of the acorn squash. Remove the seeds in the middle.
Spray a baking sheet with oil and place the acorn squash on the baking sheet. Bake 25 minutes (or until the squash is soft).
While the squash is baking, cook the quinoa according to directions.
Once the quinoa is fully cooked, add the mushrooms, chopped onion, thyme, and garlic. Cook for about 7-10 minutes.
Remove the squash from the oven and stuff with the quinoa mixture. Add parsley garnish and serve.