Slice each zucchini lengthwise and score the flesh in a crisscross pattern. Sprinkle with salt and let sit for 10 minutes to draw out moisture. Pat dry with a paper towel.

Heat 1-2 tablespoons of olive oil in a large nonstick pan over medium heat. Place the zucchini flesh-side down and sear for about 5 minutes per side until golden brown.

In a small bowl, combine 3 tablespoons of olive oil with minced garlic, chopped thyme, salt, and pepper. Mix well.

Brush the garlic mixture onto the flesh sides of the seared zucchini steaks. Sprinkle with grated Parmesan cheese. Transfer to the oven or air fryer and cook for an additional 15 minutes. Remove from the oven and top with shredded mozzarella cheese. Return to the oven for 1-2 minutes until the cheese melts.

Garnish with fresh basil leaves and chili pepper flakes before serving.