When I began catering dinners and parties, my brochure, a study in overreach, was cluttered with the kinds of recipe titles guaranteed to let my clients know their guests would be “impressed” with the food. With one exception: There, among all the extravaganzas, was “Grandma’s Banana Cake”—and everyone asked for it.

I often leave off the chocolate frosting and serve this cake with just a sprinkling of powdered sugar. But the chocolate-banana combination really makes it. Substituting