Where can I find the story of Gajanan Maharaj meeting Mhalasapati in the Khandoba temple?

The story you're asking about does not appear in the provided text, as it was not Gajanan Maharaj who met Mhalasapati. According to Chapter 0, the individual who entered the Khandoba temple wearing a kafni, cap, and dhoti was the person Mhalasapati greeted by saying, "Aavo Sai Baba." This encounter, described in Chapter 0, is a pivotal moment in the origin story of Sai Baba, as it is when he received the name he would be known by for the rest of his life. The text does not mention Gajanan Maharaj in this context.