Preheat your oven to 180 C or 350 F.

In a bowl, whisk or sift together the flour, baking powder, salt and coffee/ espresso. Keep aside.

With a wooden spoon or electric mixer , beat the butter and sugar together until light and fluffy. This will take 4-5 minutes.

Beat in the milk and vanilla extract .

Add the flour mixture and beat until a soft dough forms.

Add the chocolate chips or chunks if using and mix into the dough.

Form a log approximately 2 inches wide ,1 inch high and 10 inches long on a parchment lined baking sheet.

Bake for 18- 20 minutes until the top is cracked .

Remove from oven and let cool for 10 minutes or so. Reduce oven temperature to 120 C / 250 F.

When the log is cool enough to handle , slice it obliquely into pieces of 1 inch thickness (from one short end to another).

Place the slices (cut side up) on the parchment lined baking sheet .

Bake at 120 C/ 250 F for 10 - 15 minutes.

Let cool for few minutes on the baking sheet and then completely on a wire rack.