Slice the round bread in half horizontally. Spoon or drizzle some of the olive oil from the olive salad onto the bottom bread (the base). You can drizzle it on the top side too.Olive oil also works.
Layer the meats, one layer at a time, covering the entire base of the sandwich once. The deli meat should be sliced thin but not shaved. Traditionally layered with the Capicola (or honey ham) first, then the Genoa salami, then the Mortadella. Top with the sliced Provolone. Some local restaurans also add a thin layer of sliced Mozzarella or Swiss in addition to the provolone. This is a personal preference.
Spoon the olive salad over the cheese, starting from the center out, spreading it all around, leaving about an inch from the edge. I typically hold back some of the oil in the jar. Close the sandwich and gently press down to let the top bread absorb some of the olive salad's oil.
Serving:
Using a bread knife, slice the Muffuletta into 4 or 6 pieces and enjoy immediately.
Want to enjoy it warm? Place the whole sandwich, before slicing, on a large baking sheet, and warm it up for 5 minutes in a 350F preheated oven. Because it's going in the oven fresh and for a short time, there's no need to wrap it in foil.
Storing Leftovers & Reheating:
Wrap it tightly in plastic wrap or a zip and refrigerate for up to 3 days. To reheat it, preheat the oven to 350F, wrap the muffuletta in foil (a piece or the entire thing) and bake it for 15 minutes, until the cheese is melty and the meats have heated through.