Preheat oven to 180 degree C. Line a baking pan with parchment and set aside

Take butter, sugar and vanilla in a bowl and cream well.

Add in egg and mix well.

Add in cocoa powder and mix well.

Add in flour, baking powder and salt and mix well.

Add in chocolate chips and mix well.

Take small portion of the dough and roll it into a ball.

Arrange it in a parchment lined baking sheet and bake for 13 to 14 mins.

Now remove it and cool down.

Now take two cookies, spread nutella over it and sandwich with other cookie.

Serve.