Marble Bundt Cake

A reader recently asked me if I had a recipe for marble cake, and I was (quietly, politely) aghast. People eat it...by choice? I'm sorry if it's your favorite and now we cannot be friends, but I'd only experienced it in settings where it was just one step above no cake at all, usually dry and managing to taste like neither chocolate nor vanilla. In life, but in cake baking especially, I think we should all aspire to do one thing really well before making things more complicated. I'm so glad she pressed me, because it led me to read about the cake's origins in Germany, where it is known as Marmorkuchen, a deeply beloved birthday standard. This inspired me to do some fancy fractions with a favorite rich chocolate cake to divide it into vanilla and dark-chocolate parts. It was a very good cake, but this one is even better, thanks to a friend and fellow food blogger, Luisa Weiss—who lives in Berlin and wrote Classic German Baking, a book no baker should miss—who, from a neighbor, learned a trick of using melted white chocolate in the vanilla portion instead of leaving it plain. But don't run away if you don't like white chocolate. Here, it adds a complex toastiness, and makes a luxurious textural match for the chocolate swirls—not something you endure just to get to them.