Oven Baked Garlic Mushroom Rice

Name: Oven Baked Garlic Mushroom Rice
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Ingredients: 2 cups (400 grams) uncooked long-grain white rice (, or basmati or jasmine (it won't work as written with any other rice)); 3½ cups (840 mls) vegetable or mushroom stock; 1 medium onion (, diced); 5 to 10 cloves garlic (, minced (adjust amount to suit your tastes)); 1½ teaspoons fine sea salt (, plus a little more for seasoning the top); ¾ teaspoon ground black pepper (, plus a little more for seasoning the top); 1 teaspoon dried thyme; 1 teaspoon dried rosemary; 6 heaping cups (550 grams) sliced mushrooms (, white or cremini (chestnut in the UK)); 3 tablespoons olive oil ( or melted vegan butter (optional - omit for oil-free))