Preheat oven to 180 deg. C and prepare the baking tin; keep aside.
Melt the butter and dark chocolate in a double boiler or microwave oven (I have kept in microwave oven for 1 minute). Take it out and give it a mix. Allow to cool.
Sift together flour, salt and keep aside.
In a bowl, beat the eggs with the caster sugar (powdered) and vanilla essence.
Stir the chocolate butter mixture and then fold in flour and nuts or chocolate chip.
(Remember to cool down completely, otherwise it will become scrambled egg)
Pour the cake batter into the prepared baking tin and bake on preheated oven at 180 deg. C for 25 – 30 minutes or until a toothpick inserted into the center of the cake comes out clean.
(When it is ready, the top should be in light brown colour, but the middle is dark and dense).
Cut into pieces and enjoy the brownies with ice cream or eat as it is.