Combine the butter, sugars and vanilla in a bowl.
Add the egg and mix well.
Sift in the dry ingredients and incorporate them with a spatula.
Add the chocolate chips and mix well.
Cover the bowl with plastic wrap and place in the fridge for 30 minutes.
Take pieces of 40g each and shape them into small discs.
Sprinkle each cookie with fleur de sel.
Bake in the preheated oven at 190C for 10-12 minutes. Do not overbake them as they will dry out.
Enjoy!