In a medium bowl sift together flour, baking powder, cocoa, espresso powder and salt. Set aside.
Cream butter and brown sugar until light. I will usually use an electric hand held mixer.
Beat in the egg.
Add the cooled chocolate and mix until well incorporated.
On low speed, gradually add the flour mixture and beat until just combined.
Add the milk and once again, beat only until combined.
Turn out onto a piece of plastic wrap. Shape into a flat 1/2 inch rectangle and place in freezer for at least 45 minutes.
Preheat oven to 350 ºF/175 ºC.
Line baking sheet with parchment paper. Set aside.
Place 1/2 - 3/4 cup of confectioners' sugar in a bowl.
Cut square of dough into 30 (1/2-3/4 inch) squares. (I prefer small cookies, feel free to make larger cookies).
Roll each piece into a ball and then roll in icing sugar. Ensure that each ball is thickly coated with the icing sugar.
Place on baking sheet about 2 inches apart. Continue to roll until all of the dough is used.
Bake for about 12 minutes.
Cookies will be soft. Allow to cool down before transferring to wire racks to cool down completely.
I have often been asked about the type of cocoa I use...I prefer to use Rodelle baking cocoa (it's available at Costco or amazon).Please keep in mind that the nutritional information provided below is just a rough estimate and variations can occur depending on the specific ingredients used. *adapted from Martha Stewart