This “plain” recipe holds little more than what the title tells, yet tastes deeply delicious. The bosky, peppery mushroom juices are the sole source of moisture and mingle mysteriously with the sweet squash. Choose sturdy white chanterelles, which are especially meaty, or large golden chanterelles. The tawny trumpets and saffron squash make a handsome embellishment for pork, duck, chicken, or pheasant. For a vegetarian main dish, add cooked kamut or wheat grains, then stir in butter to bind and gloss.