Creme Brulee French Toast

1/2 cup (1 stick) unsalted butter
1 cup packed brown sugar
2 tablespoons corn syrup
1 (8 to 9) inch round loaf Challah bread
5 large eggs
1 1/2 cups half and half
1 teaspoon vanilla
1 teaspoon Grand Marnier (optional)
1/4 teaspoon salt

In a small heavy saucepan melt butter with butter with brown sugar and corn syrup over moderate heat, stirring, until smooth and pour into a 13 by 9 by 2-inch baking dish.

Cut 6 (1-inch) thick slices from center portion of bread, reserving ends for another use, and trim crusts. Arrange bread slices in one layer in baking dish, squeezing them slightly to fit.

In a bowl whisk together eggs, half and half, vanilla, Grand Marnier and salt until combined well and pour evenly over bread. Chill bread mixture, covered, at least 8 hours and up to 1 day. You can also freeze it once the bread soaks up the egg mixture. Remove from freezer night before and place in fridge - may take a little longer to cook if still a little frozen in the morning.

Preheat oven to 350 degrees F and bring bread mixture to room temperature. Bake uncovered, in middle of oven until puffed and edges are pale golden, 45 minutes to 1 hour.