Preheat oven to 425#161#F. Place squash cut side down in 8x8x2-inch glass baking dish. Cover dish tightly with plastic wrap. Microwave on high 10 minutes. Pierce plastic to let steam escape. Uncover and turn squash halves cut side up. Season cavities with salt and pepper. Combine dried cranberries and hot water in small bowl. Melt 3 tablespoons butter in heavy medium skillet over medium heat. Add mushrooms, onion and sage and saute until beginning to soften, about 5 minutes. Add breadcrumbs and stir until crumbs brown lightly, about 3 minutes. Mix in cranberries with soaking liquid. Season to taste with salt and pepper. Mound stuffing into squash halves. Dot with remaining butter. Bake until heaedt through and crisp on top, about 10 minutes.