Preheat the oven to 350°F (175°C) and grease a muffin tin with cooking spray or butter.
In a large bowl, whisk together the eggs, milk, sugar, vanilla extract, cinnamon, and salt until well combined.
Add the bread cubes to the egg mixture and gently fold until all the bread is soaked. Let it sit for about 10 minutes to absorb the liquid.
Spoon the mixture evenly into the prepared muffin tin, filling each cup about 3/4 full. If desired, sprinkle chopped nuts or chocolate chips on top of each muffin.
Drizzle the melted butter and maple syrup over the tops of the muffins.
Bake in the preheated oven for 20-25 minutes, or until the muffins are golden brown and a toothpick inserted in the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack. Serve warm with additional maple syrup if desired.