Plug in and heat up your waffle iron.
Slice the bread into slices at least one-half inch thick.
5 slices bread
Combine the ingredients for the mixture (eggs, half-and-half, orange zest, orange juice, Grand Marnier, vanilla, and salt) in a large measuring cup (e.g. 4 cup) or small bowl.
4 eggs, ½ cup half and half, 1 small orange, 1 teaspoon vanilla extract, 1 pinch salt, 1 tablespoon Grand Marnier
Use a shallow baking dish just large enough to accommodate two or three bread slices. Add a quarter of your French toast mixture, put the bread in the dish and pour another quarter of the mixture over it to soak.
When your waffle iron is hot, brush or spray oil to lightly coat if using.
neutral oil or cooking spray
Carefully remove a slice of bread, letting the excess French toast mixture drain back into the baking dish, and place it on your waffle iron. Add another slice of bread to the dish and a bit more French toast mixture to the top while the waffle cooks.
Cook the French toast waffle until it is crisp and cooked through This time will vary depending on your waffle iron, the thickness of your bread and how much mixture it has soaked up.
Repeat with the remaining slices of bread, using first ones that have been soaking the longest.
Serve warm with maple syrup, powdered sugar, or jam. If you want to serve them all at once, you can keep the French toast waffles warm in a 200℉ oven.