HE's revered as the mischievous "makhan chor", but Krishna's fondness for butter in the Mahabharata has more meanings than the literal.
Butter, as per experts on the scriptures, signifies the purity of the human soul. Krishna 'steals' the butter not because he can't get it by less clandestine means, but to emphasise that he can captivate our hearts and souls even when we are reluctant to submit ourselves to his power.
When he breaks the pot in his quest to obtain the butter, this action too has a spiritual meaning. The broken pot signifies the container of our souls — the human body — and how Krishna alone can, with his grace, release us from our earthly cage and the cycle of rebirth, therefore granting us salvation or moksha.
Similarly, each of the acts leading up to the making of butter — the "starter" needed to prepare the yoghurt from milk, the boiling of the milk, and the churning of the yoghurt — is a stand-in for the devotee's desire to know/be one with god.
When butter is offered to Krishna on Janmashtami or on other occasions, it is a metaphor for the devotees' love. If it is selfless enough, Krishna will accept the offering.
Krishna's avatar as the cowherd, lover of milk and butter, charmer of Radha and the gopis, also speaks to the nurturing side of Mother Earth. When she is treated with respect and the relationship between her and humans is symbiotic, she gives forth her bounty of nourishment. In this avatar she is Gauri. (On the flip side, we see Mother Earth as Kali, feeding on blood when she is disrespected.) As a cowherd who cares for his flock, Krishna indicates how one must treat earth in order to be nurtured by her in turn.
Apart from Ganpati, Krishna is one of the Hindu gods around whom food-related myths abound. From his indication of the number of soldiers who would lose their lives on the battlefield each day, via the media of picking out peanuts from the pudding served to him by the King of Udupi, to his deep appreciation for Sudama's fistfuls of rice, and his aid to Draupadi with the Akshaya Patra during sage Durvasa's visit, food always has a deeper meaning when it comes to Krishna, and it is up to us to discover these and deepen our understanding.