For the Chicken Marinade:

1. In a gallon plastic bag, combine chicken breasts, pesto, olive oil, lemon juice, lemon, salt and pepper. (Optional-Use a chicken tenderizer to beat the chicken so each half will be thinner and more tender.) Shake until chicken is well coated.
2. Let marinade in refrigerator for 30 minutes to an hour.

Cooking the Chicken:

1. On the stove, heat a large frying pan to medium high. Place chicken breasts in pan and cook on both sides for about 5 minutes. (Cooking time will vary depending on the thickness of meat. Check chicken in the thickest part making sure it is white and juices run clear when cut.)
2. Allow chicken to cool for a few minutes.
3. Change oven to Broil. Place shredded mozzarella cheese on chicken.
4. Cook in oven for 2 minutes. Cheese should be golden brown and melted.

Making the Sandwich:

1. On the stove, heat a medium frying pan to medium high heat.
2. Butter both sides of bread with butter. Place bread in pan and allow to brown until there is a golden brown color, about 4 minutes per side. Allow to cool for a couple minutes.
3. Spread a thin layer of pesto on toasted bread. Put chicken on top. Then top with desired toppings! Tomatoes, greens, and whatever else your heart desires.
4. Serve warm and enjoy!