Delicious vegetarian recipe from Olive Magazine. You can use any type of mushroom you like, although the Japanese ones may give better flavor. The pre-cooked vacuum packed chestnuts work perfectly in this recipe.
Put the rice, squash, chestnuts, soy sauce and mirin in a small sauce pan with a lid, lay the musrooms on the surface stalk side down. Pour the vegetable stock over the rice to cover it by about 1/4 inch, bring to a simmer, cover and cook for 15 minutes or until the rice is tender.