Preheat the oven to 350°F (175°C) and grease a muffin tin with cooking spray or butter.
In a large mixing bowl, combine the bread cubes and milk. Let it sit for about 10 minutes to allow the bread to soak up the milk.
In a separate bowl, whisk together the eggs, 1/4 cup sugar, vanilla extract, 1 teaspoon cinnamon, and salt until well combined. Pour this mixture over the soaked bread cubes and gently fold until the bread is evenly coated.
Spoon the mixture into the prepared muffin tin, filling each cup about 3/4 full. 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.
While the muffins are baking, mix together 1/2 cup sugar and 1 tablespoon cinnamon in a small bowl for the topping.
Once the muffins are done, remove them from the oven and let them cool for about 5 minutes. While they are still warm, brush the tops with melted butter and sprinkle the cinnamon sugar mixture generously over each muffin.
Serve warm or at room temperature. Enjoy!