Keep in mind that times are approximate - I chill the dough overnight - you can chill for just 4 hours before baking if you like. Baking depends on how many cookies you can bake at once.
In a medium bowl whisk together the flours, salt, espresso powder. Add in the chopped chocolate and stir well.
In a stand mixer or a large mixing bowl using a hand mixer, cream together the butter and sugars until light and fluffy. Add in the yolks and vanilla and mix again until well combined. Scraping down the sides of the bowl when needed.
Add in the flour mixture and stir until combined and no flour streaks remain.
Divide the dough into two pieces and roll out into 7-8 inch (18-20 cm) logs. Wrap tightly with wax or parchment paper, twisting the ends closed and freeze for a few hours up to overnight. I prefer to freeze the dough overnight.
When ready to bake, heat oven to 350 Deg F (180 c) and prepare baking sheets with parchment paper.
Measure out ½ inch (1.3 cm) slices in each log and slice all the way through, turning a quarter turn every so often to keep the slices round. Reshape slightly round if needed.
Place on the prepared sheets an inch or so apart and bake for 14-16 minutes until slightly puffed and set, do not over bake.
Let cool for 5 minutes then cool completely on a wire cooling rack
Melt the chocolate either in a double boiler or microwave safe bowl, and pour into a bowl that will make the chocolate deep enough for the cookies to be half dipped.
Set out a baking sheet with wax paper. Dip each cookie halfway into the chocolate then sprinkle with little coffee salt then a little turbinado sugar.
Set in the freezer to harden the chocolate.
Keep the cookies stored in an airtight container or freezer safe bag in the freezer for maximum freshness and so the chocolate doesn’t melt.