Preheat oven to 350 degrees F. Cook pasta shells according to package directions; drain. Rinse with cold water; drain again.
Meanwhile, for filling, in a medium microwave-safe bowl combine broccoli and the water. Cover with waxed paper. Microwave on 100 percent power (high) for 2 minutes; drain. Stir ricotta cheese and the 1/2 cup mozzarella cheese into cooked broccoli. Spoon filling into shells.
Arrange filled shells in an ungreased 2-quart rectangular baking dish. Spoon pasta sauce over shells; sprinkle with the 2 tablespoons mozzarella cheese. Bake, uncovered, about 15 minutes or until heated through.