Combine the cherries and rum in a small saucepan and bring to a simmer over medium heat. Remove from the heat and allow to steep for 10 minutes to soften. Cut the chocolate babka into 1 1/2-inch cubes. Spread out evenly on a baking sheet and bake until browned around the edges, 7 to 8 minutes. Remove from the oven and set aside. Lightly butter the bottom and sides of a 9 by 13-inch baking dish. In a large mixing bowl, whisk together the milk, eggs and granulated sugar until combined. Add the toasted babka and rum and cherries and mix well. Pour the mixture into the prepared baking dish. Place on a baking sheet (to catch any spillover) and bake in the oven for 35 to 40 minutes; the pudding is done when lightly browned around the edges and the mixture springs back when pressed gently in the center. Let cool at least 15 minutes before serving.
In a medium bowl, combine the heavy cream, confectioners¿ sugar, orange zest and vanilla. Beat until soft peaks form. Serve bread pudding warm with dollops of whipped cream on top and garnished with shaved chocolate.