Wash and dry all produce. Trim stem ends from zucchini, then halve lengthwise. Slice halves lengthwise into 1/4-inch-thick planks. Place in a medium bowl and toss with a large drizzle of olive oil. Season with salt and pepper. Set aside. Split ciabattas in half, then brush cut sides with a drizzle of olive oil.

Preheat a grill for direct heat and brush grates with a drizzle of vegetable oil (TIP: If cooking indoors, heat a grill pan or large pan over medium-high heat). Place ciabattas on grill or in pan cut-side down. Toast until light golden, 2-3 minutes. Set aside on a plate.

In a large bowl, mix beef, half the Parmesan, Italian seasoning, salt, pepper, and a pinch of chili flakes (use more for extra heat). Shape into four 1-inch-thick patties. Lightly brush grill grates with another drizzle of vegetable oil (or heat a drizzle of oil in pan). Add patties and cook until marks appear on bottom, 4-5 minutes (don’t flip just yet).

While patties cook, slice mozzarella into four equally thick slices. Slice tomato crosswise into four rounds. Pick basil leaves from stems; discard stems. After patties have cooked 4-5 minutes, flip and cook on other side for 1 minute, then top each with a slice of mozzarella. Cover grill or pan and cook until mozzarella melts, about 3 minutes.

Mix ketchup, vinegar, and a pinch of chili flakes (use more to taste) in a small bowl. Spread mixture onto cut-side of ciabattas. Fill ciabattas with a slice of tomato and a patty each. Top patties with basil leaves. Set aside. Lightly brush grill grates with another drizzle of vegetable oil (or heat a drizzle of olive oil in your pan).

Add zucchini to grill or pan and cook until marks appear, about 2 minutes. Flip and sprinkle with remaining Parmesan. Cover grill or pan and cook until tender and grill marks appear on other side, about 2 minutes. Divide zucchini and burgers between plates and serve.