Preheat your oven to 350°F (175°C).
Grease a 9x13 inch baking dish with butter or cooking spray.
In a large bowl, whisk together eggs, milk, vanilla extract, and cinnamon.
Cut the bread into cubes and add to the egg mixture, ensuring all pieces are coated.
Let the mixture sit for about 10 minutes to absorb.
Pour the mixture into the greased baking dish evenly.
Sprinkle brown sugar over the top for extra sweetness.
Bake in the preheated oven for 45 minutes, or until golden brown.
Let it cool for a few minutes before serving.
Serve warm with syrup or fruit toppings.