Take chocolate and butter in a microwave safe pan and melt them at 30 seconds interval till they mix well.

Combine sugar and yogurt in a blender and add to the chocolate mix.

Sieve the flour, cocoa powder and baking powder and add to the above mix.

Pour the mix in a lined cake pan and bake in a preheated oven at 180 degree Celsius for 30-35 minutes till a skewer comes out clean.

Let it cool then demould and slice into pieces..