Whisk together milk, eggs, orange juice, zest, vanilla, and Diamond Crystal® Kosher Salt in a medium bowl. (This can be prepared up to 1 day in advance.)
Pour egg mixture in a shallow pan.
Dip bread into egg mixture, and soak for 45 seconds.
Melt 1/2 tablespoon butter in a large nonstick skillet over medium-low heat. Place 2 slices of bread into skillet. Cook to golden brown, about 3 minutes on each side, and keep warm. Continue with the remaining slices of bread.