Whisk together the eggs, milk, sugar, vanilla extract, cinnamon, and salt in a bowl until well combined.
Preheat a skillet over medium heat and add a generous amount of butter.
Dip each slice of stale bread into the egg mixture, ensuring both sides are well coated.
Allow excess custard to drip off before placing the bread in the skillet.
Cook the bread slices for about 3 minutes on each side, or until golden brown.
Repeat the process with the remaining slices, adding more butter as needed.
Once cooked, transfer the slices to a plate and keep warm.
Serve the pain perdu topped with maple syrup and whipped cream if desired.
Garnish with a sprinkle of cinnamon for an extra touch.
Enjoy your delicious pain perdu hot and fresh!