Pesto Chicken Sandwich on Sourdough

Steps

1. 1Place chicken breasts smooth-side up between two layers of plastic wrap or in a large disposable plastic bag and use a meat mallet or rolling pin to pound them to an even thickness. Start with the thickest part of the meat and strike it, working outward until the breast is the same thickness all over.
2. 2Sprinkle both sides of your flattened chicken breasts with Italian seasoning, salt, and pepper.
3. 3Heat an electric countertop grill or large skillet over medium heat. If using a skillet, grease cooking surface with cooking spray or a drizzle of olive oil. Cook chicken breasts for 5 to 8 minutes per side, until an instant-read thermometer inserted into the centers of the breasts reads 165°F. Transfer chicken to a cutting board and allow to rest for 5 minutes before slicing into 1/2-inch wide strips. Wipe out your pan.
4. 4Assemble sandwiches by spreading mayonnaise (if desired) and pesto over the bread. Top with chicken, tomatoes, and cheese, and brush tops and bottoms of the sandwiches lightly with olive oil or a thin layer of mayonnaise to help them brown.
5. 5Cook sandwiches over medium to medium high heat until first side is toasted and flip. The sandwiches are done when both sides are golden and the cheese is melted. If making in a skillet, you will probably only be able to fit two sandwiches at a time in the pan. Place cooked sandwiches on a plate in a warm oven while you repeat the process with the last two sandwiches to keep them warm.