Preheat the oven to 150c. Place the coffee, butter, brown sugar and chocolate in a saucepan. Stir over a low heat until the sugar dissolves and the chocolate melts.
Pour into a mixing bowl. Cool to room temperature.
Add the eggs and beat well. Sift the dry ingredients and add. Mix well.
Pour the batter into a greased and lined 28 x 18 cm slab pan. Bake at 150c for 1 – 1 1/4 hours until a skewer inserted in the cake comes out cleanly.
Allow to cool in the pan. Dust with icing sugar to serve.