Preheat oven to 350°. Cook pasta shells according to package directions for al dente. Drain., Spread 1 cup sauce into a greased 13x9-in. baking dish. In a large bowl, beat cream cheese, Alfredo sauce and seasonings until blended. Stir in cheeses and vegetables. Spoon into shells. Arrange in prepared baking dish., Pour remaining sauce over top. Bake, covered, 20 minutes. If desired, sprinkle with additional Parmesan cheese. Bake, uncovered, 10-15 minutes longer or until cheese is melted.