Start by turning on the oven and set the temperatur to 350ºF/175ºC.
Mix the dry ingredients for the pie crust in a food processor
Add the egg and the cold butter. Let the food processor work for awhile until you have gotten yourself a nice dough. Roll it out and put it into a pie dish. Prick the pie it with a fork. Put it in the oven for 5-7 minutes (make sure it doesn't get burnt).
Finely chop the onions and start to fry it on low heat in a frying pan with some oil. Rinse and chop the green kale and remove the unedible parts. Put the green kale into the frying pan alongside the onion and fry until the kale has gotten some nice color. When your done frying ad the cheese and the chopped walnuts. Add some salt and pepper
Put the oven on 400ºF/200ºC. Mix the egg mixture in a small bowl. Add the filling into the pie crust and cover with the egg mixture. Bake it in the oven for 5-10 minutes or until the egg mixture has coagulated.
If you want to make it more sustainable use organic eggs and dairy products. Green kale is now in season so it's best enjoyed now. If you can't find the oat products use organic GMO free soy milk and yoghurt.