Preheat your oven to 225°F (110°C) and place a rack in the middle position.

Slice the zucchinis into very thin rounds, about 1.5 to 2 mm thick, using a mandoline or a sharp knife.

In a bowl, mix the grated Parmesan, minced garlic, a pinch of salt, and some black pepper.

Add the zucchini slices to the cheese mixture and gently toss until each round is coated. Shake off excess to avoid clumping.

Lay the coated zucchini in a single layer on a parchment-lined baking sheet, leaving space between slices for airflow.

Lightly drizzle each slice with olive oil or mist with oil spray for even coverage.

Bake for 1 hour, then check. If slices are still pale or floppy, continue baking up to 2 hours until edges are golden and centers feel crisp.

Rotate the pan if your oven has hot spots.

Remove from the oven and cool for a few minutes; they will crisp further as they cool.

Serve warm or at room temperature.