In a non stick pan over a low – medium heat add butter & oil. Slice the leek in half down the middle and then into half circles. Add the white & light green part of the leeks to the pan.
Cook for a few minutes, stirring a little. We don’t want them to go brown if possible. If they are catching, add a little water, a small splash at a time. Now add your green ends of the leek and crumble over the stock cube.
Keep cooking and stirring and adding water every now and then. I added about ¾ cup of water total. So it is nice and saucey.
Once the leeks are cooked and looking delicious, add the kale and cook for a few minutes until cooked but not floppy.