In a saucepan, combine corn syrup, butter, and brown sugar. Simmer until syrup-like, then pour into a 9×13-inch dish.
Slice bread into 12–16 pieces. Arrange over the syrup layer.
Beat eggs, milk, vanilla, and salt together. Pour over bread.
Cover and refrigerate 8 hours or overnight.
Preheat oven to 350°F (175°C). Bake for 45 minutes until golden and set.
Cut into squares, invert, and serve warm.
