Sift together the flours, cocoa powder, and baking soda.
With a mixer, beat together butter and sugar until creamy. Slowly, and at low speed, add in the sifted dry ingredients and mix until the dough has combined well and come together Turn off the mixer and stir in the chocolate chips.
Gather the dough, shape into logs, wrap in plastic wrap and refrigerate (or freeze, if baking later) for at least 3-4 hours.
When you are ready to bake, preheat oven to 350F and line a baking sheet(s) with parchment paper. Slice the logs of dough into rounds, each about a third of an inch thick. I like to flatten them a little bit with the heel of my hand before topping with the fleur de sel and placing on the baking sheet.
Bake cookies for about 12 mins and let cool completely before taking off the baking sheet.
Recipe by Saffron and Honey at https://saffronandhoney.com/chocolate-fleur-de-sel-cookies/