3 tablespoons vegetable oil
1 cup sliced shallots (about 3 medium)
1 package (8 oz) mushrooms, sliced
6 cups cubed (1-inch) challah bread
2 cups shredded fontina cheese (8 oz)
1 ½ cups diced cooked ham
2 cups half-and-half
2 teaspoons Dijon mustard
1 tablespoon finely chopped fresh thyme leaves
½ teaspoon salt
½ teaspoon pepper
1 Heat oven to 350°F. Spray 13×9-inch (3-quart) baking dish with cooking spray.
2 In 8-inch nonstick skillet, heat 2 tablespoons oil over medium-high heat. Cook shallots in oil 4 to 6 minutes, stirring frequently, until starting to caramelize; remove from skillet. In same skillet, add remaining 1 tablespoon oil and the mushrooms. Cook 4 to 6 minutes, stirring frequently, until tender and browned.
3 In baking dish, layer half of the bread, 1 ½ cups of the cheese, the shallots, mushrooms, ham and remaining bread. In large bowl, beat eggs and half-and-half with whisk; beat in Dijon mustard, thyme, salt and pepper. Pour over bread mixture, pressing down slightly. Sprinkle with remaining 1/2 cup cheese.
4 Bake 45 to 50 minutes or until golden brown and center is just set. Let stand 15 minutes before serving.