Wikia

Rock cake
Food information
Flavour(s)	Somewhat like a rock

"The rock cakes almost broke their teeth."

— Harry's and Ron's opinion on Hagrid's rock cakes^[src]

Rock cakes are a type of fruitcakes. They are supposed to look and (supposedly) taste somewhat like a rock, and even to have a hard surface, but not to resemble a rock quite as closely as Hagrid's version seemed to. Eating one of Hagrid's rock cakes was exactly like eating a rock, as they were so hard that they could break teeth instead of being a lovely treat. Ron Weasley, Hermione Granger, and Harry Potter forcibly ate a few of these whenever they visited Rubeus Hagrid. Although they complained about the rock cakes' hardness, stickiness, and tastelessness, they never had the heart to tell Hagrid this, as it would have hurt his feelings. He served them to Harry and Ron for the first time after their first week of lessons in 1991, ones that contained raisins.

During the summer holidays in 1994, Hagrid sent Harry a sack full of rock cakes, which Harry did not touch, due to his past experience with Hagrid's cooking.^[1]