Normally, Kali puja is performed on the night of Kartik Amavasya (October/November) in many parts of India, this Puja is a deep incantation to the frightening Goddess; the Mother Kali. The chief idea of the puja is to seek the help of the Goddess to devastate "Evil", in all its form.

Mythology and Goddess Kali

• When Shambhu and Nishambhu, according to the Hindu Mythology, disturbed the silence-fast of Indra, the king of Gods and their alliance fought intensively, The Gods lost all hope and the demons became stronger that the Gods took refuge in the Himalayas (Holy Mountains), the home of Lord Shiva and Parvati. The shaken gods sought protection from Mahamaya Durga, the goddess of Shakti. Kali was born from Durga's forehead as Kal Bhoi Nashini, created to save heaven and earth from the growing cruelty of the demons. Along with Dakini and Jogini, her two escorts, she set on her way to end the war and kill the devils.
• After lots of confusion and after slaughtering the demons, Kali Devi made a garland of their heads and wore it around her neck. In the bloodbath, she lost control and started killing anyone who came her way. The gods started running for their lives. The only source of protection seemed Lord Shiva, Durga's companion. After having seen the endless slaughter, Shiva devised a plan to save the world. He lay down in the path of the rampaging Kali. When the goddess unknowingly stepped on him, she regained her senses. The well-known picture of Ma Kali, with her tongue hanging out, actually depicts the moment when she steps on the Lord and repents.

This crucial day is celebrated as kali Puja, especially in the state of West Bengal. Mother Kali, also called Shyama Kali, is the first of the 10 incarnations (Avtar) of Goddess Durga Devi.

For the sweets and the Prasad meant for kali puja, please follow the link:
http://www.rumela.com/recipe/durga_puja_recipes.htm