Preparation Cut 12 (1-inch-thick) diagonal slices from bread, reserving ends for another use. Generously butter 1 side of each slice and arrange slices, buttered sides up, in 1 layer in a buttered 13- by 9- by 2-inch glass baking dish, squeezing them slightly to fit if necessary. Whisk together eggs, milk, and 1/4 teaspoon salt until combined well, then pour evenly over bread. Chill, covered, until bread has absorbed all of custard, at least 1 hour and up to 1 day, depending on bread. Preheat oven to 425°F. Bring mixture to room temperature and sprinkle bread with sugar. Bake, uncovered, in middle of oven until bread is puffed and top is golden, 20 to 25 minutes. Serve immediately.
Preparation Cut 12 (1-inch-thick) diagonal slices from bread, reserving ends for another use. Generously butter 1 side of each slice and arrange slices, buttered sides up, in 1 layer in a buttered 13- by 9- by 2-inch glass baking dish, squeezing them slightly to fit if necessary. Whisk together eggs, milk, and 1/4 teaspoon salt until combined well, then pour evenly over bread. Chill, covered, until bread has absorbed all of custard, at least 1 hour and up to 1 day, depending on bread. Preheat oven to 425°F. Bring mixture to room temperature and sprinkle bread with sugar. Bake, uncovered, in middle of oven until bread is puffed and top is golden, 20 to 25 minutes. Serve immediately.