He had never had any money for candy with the Dursleys, and now that he had pockets rattling with gold and silver he was ready to buy as many Mars Bars as he could carry – but the woman didn’t have Mars Bars. What she did have were Bettie Bott’s Every Flavor Beans, Drooble’s Best Blowing Gum, Chocolate Frogs, Pumpkin Pasties, Cauldron Cakes, Licorice Wands, and a number of other strange things Harry had never seen in his life.
Not wanting to miss anything, he got some of everything and paid the woman eleven silver Sickles and seven bronze Knuts.
-Harry Potter and the Philosopher’s Stone, K Rowling
Ok, so these aren’t really cakes per se. I was so focused on making something that oozed from the middle like a cauldron, that all I could think of was self saucing pudding. So, voila.
I, ehm, got a little overenthusiastic about the ‘oozing’. If you want to have more of a ‘cake’ try making a lava cake instead. Same kind of idea but it consists of either a chocolate or a fondant like centre that, when heated, becomes sauce. Meanwhile these self saucing puddings are best served in individual pots as their sauce is at the bottom of the pudding, not the middle.