Pierce squash several times with a fork; place in an 11 x 7-inch baking dish. Microwave, uncovered, at HIGH 6 minutes. Cut in half lengthwise; discard seeds. Place squash, cut sides up, in baking dish; add water. Cover tightly with heavy-duty plastic wrap, turning back 1 corner to allow steam to escape. Microwave at HIGH 5 minutes or until tender. Drain and cool 15 minutes.
While squash cools, melt butter in a large nonstick skillet over medium-high heat. Add onion and garlic; sauté 2 to 3 minutes or until onion is tender.
Using a fork, remove spaghetti-like strands from squash. Add strands (about 3 cups) to pan; cook 2 minutes or until thoroughly heated. Transfer to a bowl; add Parmesan cheese and remaining ingredients, and toss well.
I really love this recipe. A great way to use spaghetti squash in a different way. Just don't cook the squash too long or it becomes too wet and mushy. I just cut the squash in half first then put it in the baking dish with a little water and cover. Cooked mine about 7 mins and check to see if its done enough to pull out of the squash. If not, cook a minute at a time and check. Mine was a small squash so I think a larger one might take longer.
The flavors were great, but my squash was WAY over-cooked following these directions. Also, even though I poked holes in it, it blew out in the microwave during the first step. I think going forward, I will just roast it like I would normally do, and then follow the rest of the steps.