The Emperor's Code (The 39 Clues, Book 8‪)‬

When you're with Geronimo Stilton, it's always a fabumouse adventure!My family and I traveled to Milan, Italy, for a special event: the unveiling of the precious ancient parchment containing the secret, original recipe for panettone, a traditional sweet holiday bread. But right before the big moment, the recipe was stolen! And the thief was masquerading as... me! Could I catch the thief and clear my name?