NYT Cooking: Just east of Bologna, Italy, the walled city of Ferrara is known for la torta tenerina, a kind of chocolate cake with an almost creamy interior and a thin, crisp crust. It’s a simple confection, and even still, it’s said that every baker and home cook has his or her own recipe. This version comes from Eleonora Masiero and Ennio Occhiali at Cusina e Butega, a combin...