Preheat oven to 400°F (200°C).
Cut acorn squashes in half and scoop out seeds.
Brush the insides with olive oil, season with salt and pepper.
Place cut side down on a baking sheet and roast for 30 minutes.
In a skillet, heat remaining olive oil over medium heat.
Add onion and garlic, sauté until translucent.
Add kale and mushrooms, cook until tender.
Stir in cooked quinoa and vegetable broth, season with salt and pepper.
Remove squashes from oven, fill with the kale mixture.
Sprinkle with Parmesan cheese if using, bake for another 15 minutes.