Combine eggs, milk, 1 cup sugar, salt, 1 tsp cinnamon, vanilla, orange juice, and 2 T melted butter in a large bowl. Whisk together until well incorporated.
Use remaining butter to heavily butter a 9x13 baking pan.
Slice bread into ½" thick slices and then cut slices into cubes.
Combine remaining cinnamon and 1 T sugar.
Add bread cubes to pan and toss with cinnamon sugar mixture.
Pour custard mixture over bread cubes, pressing cubes down with a spoon to thoroughly soak bread.
Cover with foil and refrigerate at least one hour or overnight.
Preheat the oven to 325 degrees.
Bake approximately 40-50 minutes until golden brown and set.
Remove from the oven and sprinkle remaining 3-4 T of sugar over the top of the casserole in an even, heavy layer.
Set broiler on high and return to oven or use a kitchen torch to caramelize the sugar.
The sugar will turn brown and liquefy and then harden as it cools.
Serve warm with maple syrup if desired.
