Mix together the first 6 ingredients and refrigerate for 2 hours. Mix together the mustard and horseradish and spread on the bread. Butter the outside of the bread and toast on low heat until slightly crispy. Remove from heat and set aside.
Cut the bread into 2 layers horizontally. Layer half of the provolone on the bottom half of bread. Then the mozzarella and swiss cheese if you choose. Then the Mortadella, then the Capicola, salami, and the remainder of provolone. Top this with the olive salad mixture we did at the beginning. Put the top half of the bread on and press it down. Wrap in foil tightly and place on a baking sheet. Sometimes I even place a brick wrapped in foil on top to really get those flavors soaked into all the parts of the bread. Bake at 170 for 3-4 hours or 250 for 1-2 hours.
Recipe by Kitchen Belleicious at https://kitchenbelleicious.com/2012/03/19/new-orleans-muffaletta/