HEAT oven to 400°F.
LINE 15x10x1-inch pan with foil; spray with cooking spray. Mix coating mix and 1 tsp. basil in shaker bag. Add fish, 1 piece at a time; shake gently until evenly coated. Place in prepared pan.
BAKE 20 min. or until fish flakes easily with fork. Meanwhile, cook potatoes in boiling water in large saucepan 15 to 20 min. or until tender.
DRAIN potatoes; return to pan. Add milk, grated topping, cream cheese spread, rosemary and remaining basil; mash until mixture is well blended and of desired consistency. Serve with fish.
