Preheat your oven to 425°F (220°C).
Slice a thin piece off the bottom of each acorn squash to create a stable base, then cut the squashes in half and remove the seeds and membranes.
Place the squash halves cut-side up on a rimmed baking sheet.
Brush the insides with olive oil and season with salt and pepper.
For added sweetness, you may lightly brush with maple syrup.
Roast for 35-45 minutes until tender.
In a large skillet, heat 2 tablespoons of oil over medium heat.
Sauté onion, celery, and apple until softened, about 5-6 minutes.
Then, add mushrooms, cranberries, garlic, sage, thyme, cinnamon, salt, and pepper.
Cook for 7-9 minutes until the mushrooms and cranberries are tender.
If necessary, deglaze the pan with vegetable broth or white wine.
While the squash roasts, combine quinoa and broth in a medium pot.
Bring to a boil, then reduce heat and simmer with the lid on until the liquid is absorbed and the quinoa is fluffy, about 15-20 minutes.
Fluff with a fork and set aside.
Remove from heat and mix in the cooked quinoa, adjusting seasoning to taste.
Once the squash is done, fill each half with the stuffing mixture.
Optionally, drizzle with oil for a crispier topping.
Return to the oven and bake for an additional 10-15 minutes until the top is lightly browned and crispy.