Mozzarella en Carozza Sandwiches with Prosciutto and Peanut Butter

Name: Mozzarella en Carozza Sandwiches with Prosciutto and Peanut Butter
Ingredients: 1 roasted pepper, sliced; 1 cup prepared mayonnaise; 1/2 cup sour cream; 2 tablespoons peanut butter; Red pepper flakes; Kosher salt and freshly ground black pepper; 8 slices white sandwich bread; 3 tablespoons peanut butter; 3 tablespoons Dijon mustard; 1 ball mozzarella de buffalo, grated; 1/2 cup grated Pecorino Romano cheese; 2 tablespoons fresh parsley and fresh basil, thinly sliced; 4 slices prosciutto; 1/2 cup grated Parmesan cheese; 1 cup milk; Extra virgin olive oil, for greasing