The sweet richness of squashes makes them a much-loved ingredient and side vegetable in cuisines from all over the world, but that doesn't mean they can't present problems to the unwary cook. Many varieties are difficult to peel, and their high water content means that cooked or mashed squash is often watery and unappealing. If you find yourself with a bowl of watery squash at mealtime, there are several ways to thicken it.
Spread the squash in a shallow casserole or heatproof dish, dot the top with butter, and bake it for 45 minutes to one hour. The excess moisture will evaporate and the top will caramelize slightly, improving both the texture and the flavor.
Place the squash in a wide saucepan and cook it on the stovetop at moderate heat, stirring frequently to keep it from sticking and burning. This also evaporates the excess moisture, leaving the squash dryer and more concentrated.
Stir in 2 tablespoons of mashed potatoes for every cup of watery squash, and keep it warm for five minutes before serving. The mashed potatoes will disappear into the squash and help absorb any excess moisture. This works best when the potatoes are first mashed and haven't had any milk or butter added.
Whisk a small amount of potato starch, cornstarch or instant-mixing flour into cold water to make a slurry. Heat the squash in a small saucepan and stir in the starch mixture. Continue stirring until the squash has thickened and there's no starchy flavor.