Preheat oven to 190 degrees C. Grease a baking tray.
In a medium bowl cream together the butter, brown sugar and white sugar until smooth. Beat in the egg and vanilla. Sift together the flour, bicarb soda, baking powder, salt and espresso powder; stir into the creamed mixture. Finally, stir in the chocolate chips.
Drop dough by heaping tablespoonfuls onto the prepared baking tray. Biscuits should be 5cm apart.
Bake for 8 to 10 minutes in the preheated oven. For crispier biscuits, bake 2 minutes longer. Remove from baking trays to cool on wire racks.