Take a slice of bread and layer on it a slice of mozzarella, basil, and salt and pepper to taste. Top with another slice of bread and press together firmly to make a sandwich. Repeat with the rest of the bread and ingredients to make four sandwiches, and set aside.
Place the flour in a shallow bowl. In a second shallow bowl, combine the eggs and milk with salt and pepper to taste. In a third shallow bowl, blend the bread crumbs with salt and pepper to taste. Dip the sandwich first in the flour, then in the egg-milk mixture, and then in the bread crumbs.
In a 10-inch sauté pan, heat olive oil until medium hot. Place carrozza carefully in hot oil and turn with tongs, brown evenly all the way around on all sides. Remove from heat and serve immediately.
Note: It's important that the oil is not smoking. If the oil is too hot, carrozza and breadcrumbs will burn on the outside before mozzarella has a chance to melt between layers.