In a stand mixer, beat together butter, sugar, salt and vanilla for 2 minutes on medium speed, scraping bowl occasionally.
Press cooked egg yolks through a fine sieve with the back of a spoon into the mixing bowl and beat 2 minutes more, ensuring that the yolks are fully incorporated.
Stir flours to blend, then add to batter, do not overmix.
Grease and line an 8x8 pan with parchment paper. Press prepared dough into the pan, cover and refrigerate overnight.
The next day, when ready to bake, heat oven to 350 F
Take dough from the fridge and move to a large cutting board. With a serrated-edge knife, cut into 1-inch wide sticks approximately 4 inches long. Place on a prepared sheet, and dock holes in each cookie with a skewer or fork to release steam. Sprinkle with sugar or other embellishments and bake until lightly browned, approximately 16-22 minutes.
Let cool completely on a wire rack before dipping or drizzling.
Place chocolate in a small microwavable bowl. Microwave for 30 seconds on 30 percent power. Stir well and continue to microwave in 30-second intervals until chocolate is completely melted and smooth. Note: if only a few lumps remain in the melted chocolate, microwave for only 15 seconds on 30 percent power.
After cookies are fully cooled, dip them into melted dark chocolate and place on parchment paper to set. After the chocolate has set, if desired, drizzle with melted white or ruby chocolate, or, if you can source it, a bit of melted, very flavourful new raspberry Valrhona chocolate.