Whisk together the eggs, milk, orange juice, vanilla extract, and a pinch of salt in a large bowl. Strain the mixture to remove any egg that has not been fully incorporated, then whisk in the orange zest.
Melt ½ tablespoon butter in a large skillet over medium-high heat. Coat two slices of challah on both sides with the egg mixture and transfer them to the pan. Cook the first side until golden brown, about 2 minutes, then add another ½ tablespoon butter to the pan. When it’s melted, flip the bread and cook until golden brown on the second side, another 2 minutes or so. Repeat with remaining butter, bread, and egg mixture.
Serve hot or warm with maple syrup and powdered sugar, or any other desired toppings.
