Toss it in a salad - Warm, just-tender chunks of sweet squash make a wonderful add-in for a spicy arugula salad (and fall is the perfect time for cold weather-loving greens like arugula): Warm Butternut Squash and Arugula Salad.
Put the garlic head in a small ovenproof dish, garlic cooker, or pan. Pour 1/2 teaspoon olive oil over the top of each bulb and let it sink in between the cloves. Wait 2 minutes and then repeat with another 1/2 teaspoon olive oil over each garlic bulb.
Heat the olive oil in a large, heavy soup pot over medium heat and add the onion, leeks and a pinch of salt. Cook, stirring, until tender, about 5 minutes. Add the garlic and cook, stirring, until fragrant, 30 seconds to a minute. Add the turnips, potatoes, water or stock, salt to taste, and the bouquet garni.