Whisk sugar, cornstarch, salt, half-and-half, and milk in large saucepan. Set pan over medium heat. Add chocolate and whisk constantly until chocolate melts and mixture begins to bubble, 2 to 4 minutes. Stir in vanilla and transfer pudding to large bowl. Place plastic wrap directly on surface of pudding and refrigerate until cold, at least 4 hours or up to 1 day.
** Before baking, I lined the cake pans with parchment paper.
** Make sure to leave plenty of time to prepare the pudding and let it cool completely. Also let the cake cool completely.
** This cake is best when left to sit in the refrigerator for at least 2-3 hours before slicing/serving.