In a small, heavy saucepan, over moderate
heat, melt the butter with the brown sugar and corn syrup. Stir
until smooth. Pour into a 13- by 9- by 2-inch baking dish.
Cut 6 1-inch thick slices from the center
portion of bread, reserving ends for another use. Trim crusts.
Arrange the slices in one layer in the
baking dish, squeezing them slightly to fit.
In a bowl, beat together the eggs, half-and
half, vanilla, Grand Marnier and salt until well mixed. Pour evenly
over the bread.
Chill bread mixture, covered, at least
8 hours and up to 1 day.
Uncover and bring the bread to room temperature
before baking - about 2 hours ahead of time.
Bake on the center rack of a preheated
350-degree oven, until puffed and the edges are pale golden, 35
to 40 minutes. Serve immediately.