Preheat oven to 180 degree C. Line a baking sheet with parchment paper.

Take soft butter in a bowl and add in powdered sugar and vanilla. Whip this till creamy.

Add in egg and whip again till creamy.

Add in cocoa powder and whip again till creamy.

Add in flour, baking soda and salt and mix well till combined.

Now chill this dough for 1 hour.

Now take the dough and scoop it using a icecream scoop and roll it out, now roll this in some sugar and arrange it in the tray. Flatten it lightly and bake for 12 to 15 mins.

Now remove it from oven and cool it for 10 mins. Now remove that to a wire rack and cool it completely.

Serve.