1.In A Nonstick Skillet, Saute Leeks And Garlic In Oil Until Tender; Set Aside. Coat A 13-In. X 9-In. X 2-In. Baking Dish With Nonstick Cooking Spray. Arrange Basil In A Single Layer In Dish; Top With Fish Fillets. Sprinkle With Salt. Top With Leek Mixture. 2.Arrange Tomatoes And Olives Over Fish. Thinly Slice Half Of The Lemon; Place Over The Top. Squeeze Juice From Remaining Lemon Over All. Sprinkle With Pepper. 3.Cover And Bake At 425 Degrees F For 15-20 Minutes Or Until Fish Flakes Easily With A Fork. Garnish With Rosemary.