Preheat the oven to 375 degrees F (190 degrees C). Move the oven rack into the top third of the oven.
Heat olive oil in a large skillet over medium heat, and spread zucchini slices into the skillet in a single layer. If they don't fit, cook them in batches. Sprinkle pieces of garlic over zucchini, and cook until zucchini are golden brown on both sides, about 8 minutes per side. Remove from heat.
Arrange slices of zucchini in a 9x12-inch glass baking dish, alternating with slices of mozzarella cheese and tomato, so that the slices overlap each other in a neat row pattern. Sprinkle Parmesan cheese and basil over the dish, and season to taste with salt and pepper.
Bake in the preheated oven until the cheese is melted and brown and the dish is bubbling, about 30 minutes.