PIERCE squash several times with a fork or sharp knife to allow steam to escape. Microwave on HIGH 10 min. or just until soft, turning over after 5 min. Let stand 5 min.
CUT squash in half; remove and discard seeds. Using a fork, scrape insides of squash to form strands; place in bowl. Add remaining ingredients; toss lightly with fork. Spoon into one of the squash shells; discard remaining squash shell.
MICROWAVE on HIGH 2 min. or until heated through.