Preheat oven to 180 degree Celsius.
Grease and line a loaf pan.
Now we are going to melt chocolate. In order to do that, place water in a deep sauce pan, and allow it to come to boil. Lower the flame, and let it simmer. Put chocolate pieces and butter in another heatproof bowl, and hold it over the simmering water. Stir until smooth. Remove from flame, stir in milk, and set aside. Allow the mixture to cool for around 10-15 minutes.
Sift flour and keep aside.
In an electric mixer, beat brown sugar and eggs until pale and creamy. Add chocolate mixture little by little, and beat again. Add sifted flour and fold in gently. You don’t want any lumps in your batter.
Pour mixture into the loaf pan, and bake for 55-60 minutes. When done, cool it in the tin for about 15 minutes. Then, you can turn it on to a wire rack and cool completely.