Preparation

• Spray a 9-x 13-in. baking dish with cooking spray. Cut the bread slices into quarters to make squares, and arrange them in four rows in the baking dish.
• Whisk the eggs until the whites and yolks are well-combined. Whisk in half-and-half, brown sugar, vanilla, cinnamon, and salt. Slowly pour over the casserole, letting it seep down into the bread. Cover with plastic wrap and let stand at room temperature for 1 hour.
• Meanwhile, preheat the oven to 350°F.
• Stir together the brown sugar, flour, cinnamon, and nutmeg in a small bowl. Work in the softened butter until the mixture forms a thick paste. Refrigerate until needed.
• Remove the plastic wrap from the casserole, and crumble the topping over the top of the casserole. Bake, uncovered, for 45 to 50 minutes or until set and golden brown. A knife inserted into the center should come out moist, but clean.
• Let stand for 20 minutes on a cooling rack before serving the casserole warm, dusted with powdered sugar.