Step 1

In a mixing bowl cream together the room temperature butter and the powdered sugar using a whisk. Add the egg yolk and room temperature ristretto (espresso) coffee and whisk to combine.

Step 2

Sift together the flour, cocoa powder, and vanilla powder and add to the bowl. Fold everything together with a rubber spatula and pour onto a lightly floured surface. Knead lightly just to make sure there are no flour pockets and everything is well combined. Shape into a ball and wrap tightly in plastic wrap. Place in the fridge for one hour.

Step 3

Remove from the refrigerator and take off the plastic. Divide in half or quarters (depending on your table size) and roll out a log about 2 cm in diameter. Cut pieces out every 1.5 cm. You'll be able to make about 36-40 total cookies.

Step 4

Roll a piece into a ball between your palms in a circular motion. Then roll between your palms once in an up down motion to turn the ball into an oval. Use your thumb and forefinger to squash the ends flat, and place the cookies on a silicone or parchment lined baking tray.

Step 5

Use a very thin knife to bisect the cookie balls a little less than half way down. If you don't have a super thin knife, then don't go as deep.

Step 6

Place the tray into the freezer for 15 minutes. Preheat your oven to 165 Celsius on convection.

Step 7

Take the cookies tray out of the freezer and place in the oven about 20 cm (8 inches) from the top. Bake for 12 minutes exactly, then remove the tray and place on your counter top. Let rest for 5 minutes before removing them from the tray.