PREHEAT oven to 350° F.
PLACE cheese, flour and thyme in paper bag. Individually coat fish by gently shaking in bag; discard coating ingredients. Place fillets in baking pan with rack.
BAKE for 20 minutes or until fish flakes easily when tested with a fork.
PREPARE pasta according to package directions.
HEAT large, nonstick skillet over medium-high heat. Add onion, mushrooms, green onions and garlic. Cook, stirring frequently, until onions are tender. Season with salt and ground black pepper.
PLACE pasta on oven-warmed plates. Attractively arrange fish over pasta. Serve with mushroom medley over fish and pasta. Garnish with fresh thyme, if desired.