Rinse then dry the kale leaves. Remove centre stalks ensuring all the harder, stem-like bits are gone and tear the leaves into bite size pieces, then toss in the oil and sprinkle with the salt, pepper and chilli flakes.
Arrange the kale in a single layer on a baking tray and bake for around 5-10 minutes, or until crisp (I usually give them a little move about in between to ensure all sides are crispy). Transfer to a rack to cool, then serve.