Place bread slices in single layer in large shallow baking dish; set aside. In medium-sized bowl, whisk together milk, eggs, sugar, vanilla and lemon peel; pour evenly over bread slices; cover and refrigerate until milk mixture is absorbed, at least 1 hour or overnight. Preheat oven to 400 degrees.
Brush jelly roll pan (15 1/2 x 10 1/2 x 1 inch) with 2 tablespoons of the butter; place pan in oven until very hot and butter is melted, but not browned, about 3 minutes. With wide spatula carefully place bread slices in single layer in jelly roll pan. Bake 20 minutes; turn; brush tops with remaining 2 tablespoons butter; continue baking until browned and lightly puffed, about 15 minutes. Place French toast on large serving platter; sprinkle with 10x sugar.
