Preheat your oven to 400°F (200°C).

In a medium pot, bring water to a boil and add butternut squash cubes. Cook until fork-tender, about 10 minutes. Drain and set aside to cool.

In a large skillet, heat olive oil over medium heat. Add chopped onion and sauté until translucent, then stir in garlic, sage, thyme, salt, and pepper for additional flavor.

Combine cooked quinoa, butternut squash, dried cranberries, and chopped walnuts with the sautéed aromatics. Mix until heated through.

Prepare the portobello mushrooms by cleaning and brushing with olive oil, gill side up, on a greased baking sheet.

Spoon the filling into each mushroom cap, packing it lightly without overfilling.

If desired, sprinkle crumbled feta cheese over the stuffed caps.

Bake for 20-25 minutes until tender and golden. Keep an eye on them as they cook.

Garnish with fresh parsley before serving warm.