Pierce squash several times with a fork or sharp knife to allow steam to escape. Microwave on HIGH for about 10 minutes or until just soft, turning over after 5 minutes. Let stand 5 minutes.
Cut squash in half. Remove and discard seeds. Use a fork to scrape the insides of the squash to form strands; reserve one squash shell. Toss with cheeses, tomatoes and parsley.
Spoon squash back into shell and microwave on HIGH for 2 mintues to heat through.
Makes 6 (1/2 c) servings.