"Hagrid . . . was pouring boiling water into a large teapot and putting rock cakes onto a plate. . . . The rock cakes were shapeless lumps with raisins that almost broke their teeth, but Harry and Ron pretended to be enjoying them as they told Hagrid all about their first lessons. Fang rested his head on Harry's knee and drooled all over his robes."
—J.K. Rowling, Harry Potter and the Sorcerer's Stone
My husband made rock cakes out of my new cookbook, Vintage Cakes, on Sunday. (Tiger Lily made the tiny ones.) His version was much better than Hagrid's; no one broke any teeth. They are very filling, though.
I have really enjoyed reading through Vintage Cakes so far and I look forward to baking from it more (like for my birthday this week!). If you want to make rock cakes and don't have the book, a quick internet search will provide dozens of options for recipes.