In a bowl, whisk together eggs, milk, cream, orange juice, vanilla, nutmeg and salt.
Spread bread out in 1 layer on a large rimmed baking sheet, and pour the custard over bread, cover with plastic wrap, and let soak in the refrigerator overnight.
Flip the bread at some point before cooking (at least one hour before baking).
Pre-heat oven to 375 degrees.
In a medium bowl, whisk together brown sugar and butter. Pour mixture onto another large rimmed baking sheet, using a spatula if necessary to spread into an even layer.
Transfer soaked bread to sugared baking sheet, placing slices on top of the brown sugar mixture. Bake for about 25 minutes, or until tops are golden brown and sugar is bubbling.
Serve immediately while still hot, with the crunchy brown sugar side up, spooning more of pan syrup over the top.