Melt butter in microwave or in pan.

Now add in sugar and beat. Next add in egg one by one beating each time.

Add in vanilla essence and beat. In a bowl mix maida, cocoa and baking powder and add this too by first mixing with spatula n then lightly beat it.

Now add sour cream n beat. Finally fold in chocolate chips.

Take an 8 inches square pan,greased n lined with butter pan. Pour this mixture into it and bake at 165 degrees for 20 mins.

To check whether these are done or not insert a shashlik stick, it shouldn't be clean but some mixture should stick to itotherwise it will be turned into a cake or will be overcooked.

Let it cool n cut into slices. When not in use keep it in an airtight container to maintain its freshness.

Enjoy with tea or coffee.