As a father I am constantly sneaking extra greens into my daughter's food. This is the easiest way to do it.
Remove the stalks from the kale and place on a baking tray in the oven at around 100 degrees c for about 20 minutes. When it's crisp it's done.
Keep an eye on it in case it goes brown, which you don't want because it becomes bitter. Crumble between your fingers to make a rough powder.