Preheat your oven to 350°F (175°C).
In a large bowl, whisk together the eggs, milk, sugar, vanilla, cinnamon, and salt.
Add the cubed bread to the mixture and stir until well coated.
If using, fold in the raisins gently.
Pour the bread mixture into a greased baking dish.
Drizzle the melted butter over the top of the pudding.
Bake in the preheated oven for 45 minutes, or until set and golden brown.
Let it cool for a few minutes before serving.
Dust with powdered sugar if desired.
Serve warm or at room temperature.