To make the filling: In a medium size skillet, cook sausage, onion, green pepper, red pepper and ¼ teaspoon Italian seasoning until no pink remains in sausage. Remove from heat and drain well. Add pepperoni and olives, mixing until evenly distributed. Set aside to cool then add shredded cheese. Mix well.
To assemble. Preheat oven to 350°F. Place 2 (24 inch) pieces of heavy duty foil across each other on a large sheet pan. Spray foil with cooking spray. Set aside.
Use a serrated knife to cut loaf on the bias in a criss cross pattern 1 inch apart without cutting all the way through to the bottom. Center bread in foil.
In a small bowl, mix together melted butter, ¼ teaspoon Italian seasoning and garlic. Gently pull apart bread cuts and brush between each, reserving ½ for the top. Arrange quartered cheese slices in cuts, spoon sausage mixture evenly between cheese slices.
Brush top with reserved butter and sprinkle all over with Parmesan cheese.
To bake: Pull foil up loosely and seal. Bake for 30 minutes, then pull foil back and bake for an additional 5-10 minutes or just until lightly golden and cheese is fully melted.
Serve immediately garnished with fresh parsley, pulling apart pieces and dipping in warmed pizza sauce. (May brush with more butter and sprinkle with additional grated Parmesan just before serving, if desired.)