Place bread on working surface; top half of the slices with 1 slice mozzarella, 2 slices prosciutto, 1/4 cup (60 mL) arugula and remaining mozzarella slices. Cap with remaining bread.
In shallow baking dish, whisk together eggs, milk, pesto, salt and pepper. Heat oil in large skillet set over medium heat. Dip each sandwich into egg mixture, coating completely; cook, in batches, for 6 to 10 minutes, turning once, or until both sides are golden brown and cheese is melted.
· Use fresh or smoked mozzarella cheese for a gourmet indulgence.