Classic Italian Panini with Prosciutto and Fresh Mozzarella

This to me looks like the perfect busy night supper

1 (12-ounce) loaf French bread, cut in half horizontally
1/4 cup reduced-fat mayonnaise
2 tablespoons chopped fresh basil
1 cup (4 ounces) shredded fresh mozzarella cheese, divided
2 ounces very thin slices prosciutto
2 plum tomatoes, thinly sliced
Cooking spray

Hollow out top and bottom halves of bread, leaving a 1/2-inch-thick shell; reserve torn bread for another use. Spread 2 tablespoons mayonnaise over cut side of each bread half. Sprinkle basil and 1/2 cup cheese on bottom half of loaf. Top evenly with prosciutto, tomato slices, and remaining 1/2 cup cheese. Cover with top half of loaf. Cut filled loaf crosswise into 4 equal pieces. Heat a grill pan over medium heat. Coat pan with cooking spray. Add sandwiches to pan. Place a cast-iron or other heavy skillet on top of sandwiches; press gently to flatten sandwiches. Cook 3 minutes on each side or until bread is toasted (leave cast-iron skillet on sandwiches while they cook).

Source: Elizabeth Karmel, Cooking Light, MAY 2008