Sweet, soft, and flaky, and perfect with a glass of milk.
Turn the oven up to 350 F.
In an 8 inch square baking pan, break up the bread into little bits. Drizzle the melted butter over it, then sprinkle the raisins over the bread if you're using them.
In a medium mixing bowl, combine the eggs, milk, sugar, cinnamon, and vanilla and beat until well-mixed. Pour that stuff over bread bits, using a fork to lightly push it all down until bread is covered and begins soaking up the egg mixture.
Bake the pan in the preheated oven for 45 minutes. The top should be firm and springy.