Wild Mushroom and Sage Stuffed Butternut Squash

Name: Wild Mushroom and Sage Stuffed Butternut Squash
Ingredients: 1 medium butternut squash (halved lengthwise and seeds removed); 1½ tbsp extra virgin olive oil (plus extra for drizzling); 1 small red onion (finely chopped); 2 garlic cloves (minced); 3 cups mixed wild mushrooms (e.g. shiitake, oyster, chestnut, roughly chopped); 1 tsp fresh sage (finely chopped, or ½ tsp dried sage); ¼ tsp sea salt (to taste); freshly ground black pepper; 2 tbsp chopped walnuts (optional); 1 tbsp crumbled feta (or nutritional yeast, both are optional); fresh thyme (or parsley for garnish)