Place the giardiniera, green olives, kalamata olives, olive oil, and vinegar into a food processor. Process until it is almost a paste, set aside.
Cut the bread about ⅔ up from the bottom all the way across. Take out most of the bread from the bottom half, leaving about ½ inch thickness of bread left.
Add half of the olive spread, and spread it out evenly.
Layer the provolone cheese, then continue layering with the ham, salami, and prosciutto.
Finish it off with the mozzarella.
Take the top of the bread and once again scoop out most of the bread leaving a ½ inch of the bread inside. Spread the remaining olive mixture onto the bread then place it cut side down onto the sandwich.
Wrap it tightly with plastic wrap a few times so it is completely encased. Place it on a sheet tray and put something heavy on top like a 6 pack of beer or a heavy skillet. Place it in the fridge for at least 4 hours to chill or even best overnight.
Remove the plastic wrap and cut into wedges, serve immediately.
Notes
This is a great make ahead meal for dinner or lunch.
Other meats can be used, see my tips above.
I do not recommend freezing.
We like a nice soft bread since the sandwich is filling, see options on bread above.
This can be spelled Muffuletta or Muffaletta, either way is correct.
This needs to chill for at least 4 hours but overnight is best.