Arrange the bread in two layers in a 9 by 13 by 2-inch baking dish, cutting the bread to fit the dish. Set aside.
In a large bowl, whisk together the eggs, half-and-half, honey, orange zest, vanilla, and salt. Pour the mixture over the bread and press the bread down. Allow to soak for 10 minutes.
Place the baking dish in a larger roasting pan and add enough very hot tap water to the roasting pan to come an inch up the side of the baking dish. Cover the roasting pan tightly with aluminum foil, tenting it so the foil doesn't touch the pudding. Make two slashes in the foil to allow steam to escape. Bake for 45 minutes, remove the aluminum foil, and bake for another 40 to 45 minutes, until the pudding puffs up and the custard is set. Remove from the oven and cool slightly.
With a small sieve, dust lightly with confectioners' sugar and serve hot in squares with maple syrup on the side.