What is the name of the Zoroastrian book of creation?

The name of the Zoroastrian book of creation is the Bundahishn.

Its title is Middle Persian for “Primal Creation,” and the work is an encyclopedic account of Zoroastrian cosmology. It describes the creations of Ahura Mazda, the destructive challenge of Angra Mainyu, the ordering of the heavens, and the origins of living creatures and humanity.

The Bundahishn survives in Book Pahlavi and was compiled mainly in the 8th and 9th centuries CE, drawing on older Avestan traditions. It is not itself part of the Avesta, although it preserves and explains ideas rooted in Zoroastrian scripture. Readers often confuse it with the Denkard, a later Middle Persian theological and encyclopedic work, or with the Yasna and Vendidad, which belong to the Avesta and serve different ritual or legal purposes.