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. (You can also bake the squash in a preheated 350°F oven for 1 to 1 1/4 hours).