Heat the oven to 450°F. In a large bowl, toss the zucchini with 1 tsp. salt and ½ tsp. pepper and 2 Tbs. olive oil. Spread in a single layer on a large rimmed baking sheet and roast until the zucchini browns in places and is tender when pierced with a knife, about 8 minutes. Remove from the oven.

Heat the garlic with 2 Tbs. olive oil in a large skillet over medium-high heat until it starts to sizzle steadily, about 1 minute. Add the tomato, sprinkle with ½ tsp. salt and ½ tsp. pepper, and cook, tossing, until the tomato softens and becomes saucy, about 5 minutes. Remove from the heat and toss with the fresh basil. Season to taste with salt and pepper.

Grease an 8x8-inch baking dish and add half of the zucchini in a single layer. Top with half of the tomato sauce and half of the Parmigiano. Repeat with the remaining zucchini, tomato, and Parmigiano and then sprinkle with the mozzarella. In a small bowl, toss the Panko with the remaining 1 Tbs. olive oil and ¼ tsp. salt and sprinkle on top of the cheese. Return to the oven and bake until the cheese melts and the breadcrumbs brown, about 12 minutes.

Let the zucchini cool for a couple of minutes, then cut into squares. Serve immediately.