Preheat oven to 375F. Pierce squash a few times with sharp paring knife to let steam escape. Bake spaghetti squash for 60 minutes, or until a paring knife pierces easily through skin with little resistance. Let squash cool for 5 to 10 minutes. Cut squash in half, lengthwise. Remove and discard the seeds. Use a fork to scrape the squash and remove all the strands.
Heat a skillet. Add butter and garlic. Heat over low to medium heat until butter melts, stirring often. Add parsley, spaghetti squash strands and a little salt and pepper. Toss well to coat and sprinkle in the parmesan cheese.