Slice the round Italian bread in half horizontally. If desired, hollow out some of the bread from the top half to make room for the fillings.

In a small bowl, mix the olive salad with the extra virgin olive oil, dried oregano, salt, and pepper.

Spread half of the olive salad mixture evenly on the bottom half of the bread.

Layer the mortadella, salami, ham, and provolone cheese on top of the olive salad.

Spread the remaining olive salad on top of the cheese layer.

Place the top half of the bread on the sandwich and press down gently.

Wrap the sandwich tightly in plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld. For best results, let it chill for 4 hours or overnight.

Before serving, slice the sandwich into wedges and serve cold or at room temperature.