Preheat the oven to 350°. In a medium saucepan, combine the whole milk with the vanilla bean and seeds and the salt and bring to a simmer. Cover and let the milk stand off the heat for 15 minutes. Discard the vanilla bean. Add half of the chopped milk chocolate to the warm milk and whisk until smooth. Let the milk and chocolate mixture cool for 15 minutes. Whisk in the eggs.
In a 9-by-13-inch baking dish, toss the croissant pieces with the remaining chopped milk chocolate. Pour the chocolate custard over the croissant pieces; press lightly to submerge them in the custard. Bake for 30 minutes, until the bread pudding is risen and set. Let the chocolate bread pudding cool slightly, then cut it into squares and serve warm, with ice cream.