What sweet treat does the White Witch give to Edmund?

The White Witch gives Edmund Turkish Delight.

Edmund Pevensie first meets the White Witch in Narnia while she is traveling in her sleigh. She conjures an enchanted version of Turkish delight and uses it to win his trust. The confection is paired with promises that she will make Edmund a prince and eventually her heir if he brings his siblings to her.

This scene establishes the Witch's method: she exploits appetite, vanity, and resentment rather than relying only on force. Edmund's desire for more Turkish delight helps draw him back to her, even after he begins to suspect that the “Queen of Narnia” is dangerous. His betrayal places Peter, Susan, and Lucy at risk.

Turkish delight is a real confection, traditionally made from starch and sugar and often flavored with rosewater, citrus, or nuts. Lewis's fictional version is magically intensified, so the scene should not be read as an ordinary candy purchase. The treat is sometimes generically remembered as candy, fudge, or a sweet, but the canonical answer is Turkish delight.