Place 1 slice of bread on working surface. Place 2 slices of prosciutto and 2 slices of mozzarella on top of bread. Place another slice of bread on top. Trim the crusts. Cut in half forming 2 rectangles and place 2 toothpicks through each of the rectangular sandwiches to hold together. Repeat using other 2 slices of bread, mozzarella, and prosciutto. Dredge each spedini in flour then dip in egg, covering all sides. Heat about 3 inches of vegetable oil in a large saute pan over high heat. Place spedini in pan and fry on both sides until brown. Place on serving plates and remove the toothpicks.