If your bread isn’t stale, toasted it in a 300 °F oven for 5-6 minutes to dry it out. You don’t want it actually toasted, just dry.
In a wide, shallow dish, whisk together milk, eggs, vanilla, cinnamon, and a pinch of salt.
Heat a large skillet or griddle over medium heat. Once hot, melt a small amount of butter in the pan and spread it around.
Working with one piece of bread at a time, dip it in the custard mixture and let it soak for a few seconds. Then transfer to the hot skillet or griddle.
Let the french toast cook for a minute or two on the first side. Sprinkle some sugar on the french toast and give it a flip. Cook the french toast on the second side until it’s browned and the sugar is caramelized, 1-2 minutes.
Remove french toast and repeat with remaining pieces of bread. Serve warm french toast with butter and syrup.