Preheat your oven to 200°C (390°F) and line a baking sheet with parchment paper to keep things tidy.
Wash the zucchinis thoroughly, then slice them into thin, even rounds about 2-3 mm thick using a mandoline or a sharp knife. Aim for uniform slices so they cook evenly.
In a small bowl, whisk together the olive oil, a pinch of flaky sea salt, and optional spices like smoked paprika and freshly ground black pepper.
Using a pastry brush or the back of a spoon, lightly brush each zucchini slice on both sides with the seasoned olive oil mixture. Be gentle but thorough—this helps them crisp without becoming soggy.
Arrange the coated zucchini slices in a single layer on the prepared baking sheet, making sure they don’t overlap. If using Parmesan, sprinkle it evenly over the slices now for a cheesy crust.
Bake in the preheated oven for 15-20 minutes. Check around the 12-minute mark and flip the slices carefully with tongs or a spatula for even crispiness. Keep an eye on them so they don’t burn—edges should turn a deep golden brown.
Once they are golden and crispy, remove the baking sheet from the oven and let the chips sit for a few minutes on the sheet. They will continue to crisp as they cool down.
Transfer the chips to a wire rack to cool completely, which helps maintain their crunch. Serve immediately for the best texture, or store in an airtight container once cooled.
