Combine oil and garlic; brush over both sides of eggplant slices. Place on a greased baking sheet. Bake at 425° for 15 minutes; turn. Bake until golden brown, about 5 minutes longer. Cool on a wire rack.
Place half of the eggplant in a greased 1-qt. baking dish. Sprinkle with half of the basil and Parmesan cheese. Arrange tomato slices over top; sprinkle with remaining basil and Parmesan. Layer with half of the mozzarella cheese and the remaining eggplant; top with remaining mozzarella. Cover and bake at 350° for 20 minutes. Uncover; bake until cheese is melted, 5-7 minutes longer. Garnish with additional basil, if desired.