Preheat the oven to 200 degrees F.

Crack the eggs into a large mixing bowl and whisk well.  Add the milk, orange juice, orange zest, granulated sugar, vanilla extract, and salt, and whisk until well combined.  Working quickly, dip each bread slice into the egg mixture in the bowl, turning it to coat both sides with the mixture.  Transfer the coated bread slices to a plate while you finish coating the remaining slices.

Heat a small skillet over medium heat until hot, about 3 to 5 minutes.  Melt 1 teaspoon of the butter in the skillet, then add a slice of coated bread, and cook until the bread is golden brown and crusted on the bottom, about 2 minutes.  Turn with a plastic turner and cook until the second side is golden, about 1 to 1 1/2 minutes.  Transfer the French toast from the skillet to a baking sheet.  Cover lightly with aluminum foil and place in the oven to keep warm while you cook the other slices.

Repeat with the remaining slices, being sure to add 1 teaspoon of the butter to the pan before every slice.

Sprinkle the French toast with confectioners’ sugar and serve with maple syrup or pancake syrup.