Spaghetti Squash with Zucchini, Mushrooms and Onion

Pierce squash (about an inch deep) all over with a small sharp knife to prevent bursting. Cook in an 800-watt microwave oven on high power (100 percent) for 6 to 7 minutes. Turn squash over and microwave until squash feels slightly soft when pressed, 8 to 10 minutes more. Cool squash for 5 minutes.

Carefully halve squash lengthwise (it will give off steam) and remove and discard seeds. Working over a bowl, scrape squash flesh with a fork, loosening and separating strands as you remove it from skin. Stir in butter and season with salt and pepper to taste. Put on a platter.

Meanwhile, heat oil in a12-inch skillet over moderately-high heat, sauté onions and garlic, stirring frequently until golden, about 6 minutes. Then stir in zucchini and mushrooms, salt and pepper and cook, covered until softened, occasionally stirring, about 7 minutes. Spoon mixture over squash.