When it comes to French toast, the type of bread you use has a big impact on the final result. Traditional french toast is made using thick slices of white bread or brioche, but you can also use French bread or any crusty bread of your choice. Sourdough and heartier breads like whole wheat both work well in this recipe. Regular sandwich bread is not ideal, but it can work in a pinch. The most important thing is to use stale bread that is at least a few days old. This will allow it to absorb more of the custard without getting soggy.