Insert your knife 1 inch from the top edge of the loaf at a 45 degree angle and cut around the loaf until the lid comes off. Set lid aside. Pull excess bread out of the center of the loaf to create a hollow effect. Level off the inside of the lid and begin assembly. Brush the lid with some of the oil mixture from the olive salad. Spread the olive salad on the bottom half of the bread and begin to layer the sandwich, starting with the fontina cheese, mortadella, arugula, capicolla, red peppers, and finishing with the salami. Wrap the sandwich tightly with plastic wrap and put on a plate. Place a cast iron skillet on top of the sandwich to weigh it down and put it in the refrigerator overnight. Bring to room temperature before serving. Cut into wedges.
Muffuletta Olive Salad:
Combine all ingredients. Serve at room temperature.
To chiffonade, stack the basil leaves 5 or 6 high, roll up, then, with a very sharp knife, slice into fine ribbons. The salad can be made up to 1 day in advance.