Step 1

Butter a shallow 2-quart baking dish. In a large bowl, whisk together eggs, milk, sugar, cinnamon, and salt. Dip brioche in egg mixture, then arrange in dish, overlapping slightly and sprinkling raisins between slices. Pour remaining egg mixture over brioche and let stand 30 minutes or refrigerate up to overnight. Preheat oven to 325 degrees.

Step 2

Bake until puffed and custard is just set in center, 55 to 65 minutes (tent with foil, if browning too quickly). Let cool at least 15 minutes before serving.