Use a double boiler to melt the chocolate or one can use microwave too.
I use the double boiler method - Place a heatproof bowl over a saucepan of simmering hot water. The heatproof bowl should not be in touch with water below.
Melt the chocolate and butter. Remove from heat and let it cool to room temperature.
In a hand mixer or your electric mixer, beat in the eggs and sugar until thick, pale and fluffy. It should be in a ribbon stage and would change colour. This process takes around 3-5 minutes.
Add the vanilla extra and beat.
Now add the cooled chocolate mixture and beat until incorporated.
In another bowl whisk together flour, salt, baking powder.
Add dry ingredients to the chocolate mixture and stir until just incorporated.
Cover with a plastic wrap or store it in an airtight container in refrigerator until firm enough to shape into balls. This might take a few hours or overnight.
When ready to bake, preheat the oven to 165 Deg C. Line 2 baking sheets with parchment paper.
Place the sifted Icing sugar in a bowl or plate , where you would be able to roll the dough.
Take around 1-1.5 tablespoon of dough and roll into a ball.
Place it into the sugar and well coat it all over so that the chocolate is not seen.
Place the sugar covered balls on the prepared baking sheet, leaving proper space in between.
Bake cookies for 8-10 minutes or just until they are firm on the edges and still soft in the center.
Do not over bake. Remove from oven and let them cool.