Combine first 4 ingredients; add fillets, turning to coat both sides with marinade. Cover and marinate in refrigerator 30 minutes, turning once.
Remove fillets from marinade; discard marinade. Place fillets in a 7- x 5- x 1 1/2-inch baking dish coated with cooking spray. Bake, uncovered, at 350° for 20 to 25 minutes or until fish flakes easily when tested with a fork. Transfer fillets to a serving plate, and keep warm.
Coat a saucepan with cooking spray; add cheese and next 3 ingredients. Cook over medium heat until thoroughly heated, stirring frequently. Spoon over fillets. Garnish with basil leaves, if desired.