Preheat the oven to 180°C (350°F). Arrange the bread slices in a greased baking dish, overlapping slightly.
Place the chopped semi-sweet chocolate in a microwave-safe bowl and microwave in 20-second intervals, stirring until smooth and melted. Let it cool slightly.
In a mixing bowl, whisk together the eggs, milk, sugar, and salt until well combined and the mixture is slightly frothy.
Pour the melted chocolate into the egg mixture and whisk thoroughly until fully integrated, creating a chocolate custard.
Pour the custard mixture evenly over the bread slices in the baking dish, pressing down gently to soak the bread completely.
Bake in the preheated oven for 20-25 minutes, until the custard is set and the top is golden brown. You can check doneness by gently shaking the dish—only the center should wobble slightly.