If you have some lovely young kale leaves, then just blitz them straight into the pesto. Otherwise I recommend you boil the leaves first. This pesto will keep for up to a week in the fridge in a sealed glass jar. It is great spread on crackers or eaten straight from the spoon if you need a quick snack. I have only added a small amount of chilli to this in deference to The Princess. Feel free to add more if you want it spicier.