Ingredients:
180g dark chocolate, coarsely chopped
60g butter
1 ½ cup flour
¾ tsp baking powder
1/8 tsp salt
2 large eggs, at room temperature
2/3 cup granulated sugar
2 tsp coffee dissolved in 2 Tbsp of water
1 tsp vanilla extract
½ cup icing sugar, sifted
Method:
Melt the chocolate and butter together and let the mixture cool slightly.
In a medium bowl, whisk together the flour, baking powder, and salt until blended; set aside.
In the bowl of an electric mixer, using the whisk attachment, beat the eggs with the sugar at medium-high speed until pale, about 2 minutes. Reduce the speed to low and mix in the cooled chocolate mixture. Add the coffee and vanilla extract and mix until combined. Add the flour mixture and mix just until blended. Cover the bowl with plastic wrap and refrigerate for at least 1 ½ hours, until firm enough to shape (or up to 2 days).
Position a rack in the center of the oven and preheat the oven to 160 degrees Celsius.
Place the icing sugar in a shallow bowl. Shape the dough into 1 ¼ inch balls. Coat each ball well in the icing sugar and arrange on ungreased baking sheets, spacing them at least 1 ½ inches apart. Bake for 12 to 15 minutes, until their tops are cracked and their edges are set but they are still soft in the center. Let the biscuits cool on the baking sheets for 5 minutes, then transfer them to a cooling rack and cool completely.