Preheat oven to 375F. Halve squash lengthwise. Scoop out and discard seeds. Place cut side up in baking pan; add butter and garlic to hollow centers. Sprinkle with 1/2 t salt and 1/4 t pepper. Cover tightly with foil; bake 1 1/2 hours or until very tender. (To microwave: With fork, pierce whole squash several times. Place in glass baking dish. Cook in HIGH 18 minutes, turning squash every 4 minutes. Let stand 5 minutes. Place butter in small glass bowl; melt on HIGH 30 seconds. Add garlic; cook on HIGH 1 minutes; with fork, mash. Halve squash lengthwise; seed. )
Remove squash from oven; discard foil. With fork, transfer garlic to small bowl; mash. With fork, comb squash strands into large bowl. Add mashed garlic, cheese and basil; toss. Season to taste with additional salt and pepper. If desired, sprinkle with freshly grated Parmesan cheese.