Preheat Blackstone griddle to medium-high heat (375–400°F) for 5 minutes until shimmering.
Slice zucchini to desired cut style. For best results, lay on paper towels, sprinkle with salt, rest 10 minutes, then pat completely dry.
Place zucchini in a large bowl. Drizzle with olive oil and add garlic powder, onion powder, and pepper. Toss to coat. Add salt now if you skipped the salt-and-rest step.
Spread a thin layer of oil on the griddle surface. Lay zucchini flat in a single layer — do not crowd. Leave space between each piece.
Cook for 3–4 minutes without moving. Let the zucchini sear undisturbed until it releases easily from the surface.
Flip with a thin metal spatula. Cook for another 3–4 minutes until golden brown on both sides and tender throughout.
Transfer to a platter. Add parmesan, fresh herbs, lemon juice, or any finishing seasonings while still hot. Serve immediately.