Preheat oven to 350°F (175°C). Grease an 8x8-inch baking dish.
Tear bread into small pieces and place in the prepared dish.
In a mixing bowl, whisk together eggs, milk, sugar, vanilla, salt, and cinnamon until well combined.
Pour the custard evenly over the bread, gently pressing down to soak all pieces.
Let sit for 10 minutes to absorb.
Bake for 40–45 minutes, or until golden and the custard is set in the center.
Cool for a few minutes, then dust with powdered sugar and serve warm.