Heat air fryer to 350°F or conventional oven to 450°F.
Cut chicken breasts horizontally, almost in half, leaving attached at one side. Open breast so it lies flat like a book; cover with plastic wrap. Lightly pound with the flat side of a meat mallet to 1/4-inch thickness. Repeat with remaining chicken breasts.
Season chicken with salt and pepper. Spread each piece with 1 teaspoon Dijon mustard. Top with a slice of cheese, a slice of ham, and another slice of cheese. Roll chicken, from the short side, and secure with a toothpick.
Place flour in a shallow bowl. Place egg in a second bowl. Mix panko bread crumbs and grated Parmesan in a third bowl. Dredge chicken in flour, then dip in egg, and roll in the bread crumb mixture.
Place chicken, seam side down, in the air fryer basket. Spray top of chicken with cooking spray. Cook for 20 minutes or until chicken is golden brown and the internal temperature reaches 165°F. Cool slightly, remove toothpicks and slice each chicken breast into ¼-inch-thick pieces.
To bake in conventional oven: Place chicken, seam side down, on a parchment paper lined sheet pan. Spray top of chicken with cooking spray. Bake at 450°F for 20 to 25 minutes, or until chicken is golden brown and the internal temperature reaches 165°F. Cool slightly; remove toothpicks and slice each chicken breast into ¼-inch-thick pieces.
Arrange Fresh Express® Italian Lettuce Salad Blend on four plates. Top lettuce with chicken and tomatoes. Drizzle with Dijon dressing.