Arrange eggplant in a single layer in a 13- x 9- x 2-inch baking dish coated with cooking spray.
Cover; bake at 425° for 10 minutes.
Turn eggplant; cook, uncovered, 10 minutes.
Let cool slightly.
Fill each pita half with 2 eggplant slices, 1 tomato slice, 1/2 tablespoon cheese, 1/2 tablespoon onion, and sliced basil leaves.