Soak the raisins in the rum for at least 20 minutes.

Spread the bread cubes in a greased baking dish.

Whisk the milk, eggs, sugar, and cinnamon together.

Stir the soaked raisins into the custard and pour over the bread.

Let it sit 10 minutes so the bread soaks up the custard.

Bake at 350F for about 45 minutes until set and golden.