Preheat the oven to 450°F (230°C) OR to 400°F (200°C) with a fan setting (convection). Move the rack one shelf above the center.
Wash the zucchini and dry with paper towels. Cut into thick, at least 1/2 inch (1 1/4 cm) slices.
Place on a baking sheet (don´t line it with parchment paper), drizzle with olive oil and season with salt and pepper. Toss to coat. Spread the slices as much as you can.
Sprinkle zucchini with garlic powder and basil, then with grated cheeses (preferably on a Microplane).
Bake for 9 minutes then turn on the broiler (grill+fan setting) and bake for a further 2-3 minutes or until cheese is golden in color. Keep an eye on the zucchini so it won´t burn (easy is such a hot oven). Baking time may vary depending on the thickness of the zucchini slices and on the oven (every oven bakes differently).
Enjoy!