Preheat the oven to 190°C / 170°C (fan oven) / 375°F / Gas Mark 5. Wash the kale, pick the leaves (discard stalks) and dry very thoroughly. Add to a bowl with the olive oil and toss well to coat.

Lay the kale on a non-stick baking sheet in a single layer (do not overlap). Bake for 15-20 minutes, rotating the baking sheet half way. Remove from the oven when the crisps are crisp, rest for 3 minutes.