Chop the bread into cubes and place it in a 9x9 (or 11x7) baking dish.
In a large bowl, whisk together the eggs, milk, heavy cream, orange zest, vanilla, cinnamon and salt. Pour it over the bread cubes, pressing any cubes into the mixture to make sure they are moistened.
Cover the dish and refrigerate overnight, or at least for 8 hours.
Preheat the oven to 350 degrees F. Remove the dish from the fridge.
When the oven is heated, uncover the french toast. Bake uncovered for 35 to 45 minutes, or until golden brown and toasty.
While the french toast bakes, make the glaze. Whisk together the juice, zest, powdered sugar, heavy cream and vanilla until smooth.
Remove the french toast from the oven and serve. Drizzle with the orange glaze and enjoy! Sprinkle with powdered sugar if desired.