1. Slice ciabatta in half horizontally. Hollow out top and bottom halves of bread; reserve torn bread for another use. Spread Pesto over bottom half of bread. Layer prosciutto, bell pepper strips, and cheese over pesto; sprinkle with pepper. Replace top half of bread. Wrap loaf in plastic wrap and foil, and place on a plate; top with a heavy skillet filled with heavy cans. Refrigerate 2 hours or overnight.
2. Remove foil and plastic wrap; cut sandwich into 8 pieces.