Combine Dijon herb spread ingredients and reserve. Combine panko bread crumbs, Peri Peri seasoning and black pepper in a shallow dish and reserve.
Cut chicken breast in half. Pound each half to an even thickness (about 1/2-inch thick). Dip each chicken piece in beaten egg, then seasoned panko crumbs. Heat olive oil in skillet over medium heat. Pan fry chicken pieces until golden brown on each side and cooked through, about 4 minutes per side. Remove and cut each in half.
To assemble sandwiches, spread Dijon herb spread on one side of each slice of baguette. Layer with a piece of Virginia ham, Muenster cheese, half piece of breaded chicken, Muenster cheese, Virginia ham, then top with second piece of baguette. Butter both sides of each sandwich and pan grill until golden brown on each side.