Preheat the oven to 180°C.
Melt the dark chocolate, either with 60-degree water or in the microwave, being careful not to overheat it.
In a bowl, mix the melted chocolate with the butter, egg, brown sugar, salt, and instant coffee.
In a separate bowl, combine the all-purpose flour and baking powder.
Add the dry ingredients to the wet ingredients and mix until just combined.
Fold in the chopped nuts and chocolate chips.
Scoop 35g portions of the dough onto a baking sheet, spacing them apart.
Bake for 10-11 minutes, until the edges are set but the centers are still soft.
Allow the cookies to cool completely before handling.
