Cut the mozzarella into enough 1/4-inch thick slices to cover 2 slices of the bread. Reserve the remaining mozzarella for another use. Top the cheese with the remaining 2 slices of bread, to make 2 sandwiches, and press down to compact.
In a bowl, whisk together the eggs, garlic, and parsley and season with salt and pepper. Put the bread crumbs on a plate.
In a large skillet over medium-high heat, pour the in oil to a depth of 1/4-inch. When the oil is hot, dip each sandwich into the egg mixture, dredge in the bread crumbs, and fry, turning once, until crisp and the cheese has melted.
Cut each sandwich in 1/2 and serve, while still hot, with the marinara sauce on the side for dipping.
Heat the oil in a saucepan over medium-high heat. Add the garlic and cook, stirring, until fragrant. Add the tomatoes and sugar and season with salt and pepper, to taste. Bring to a boil, lower the heat, and simmer for 30 minutes.
Remove the sauce from the heat and stir in the basil and parsley.
Recipe courtesy of Vita Greco, Next Door to the Chicken Market, 2002