Preheat oven to 350 degrees and toast bread cubes until golden, for about 10 minutes. Set aside.

Heat half and half, butter, and the two bars of chocolate in a sauce pan until the chocolate has dissolved and the mixture is almost boiling, about 10 minutes. Let cool.

Whisk together eggs and sugar in a medium bowl.

Slowly whisk in chocolate milk mixture until well blended.

Stir in Kahlua, cinnamon, and raisins (if you are using raisins).

Grease a 9x13 baking dish with 1 tbsp butter and add the toasted bread cubes.

Pour the chocolate mixture over the bread cubes and let stand for one hour.

Bake for about 35 minutes or until mixture is set.

Let cool to warm, and serve. Garnish with powdered sugar.