Spray a 9x13 baking dish with cooking spray (I used an au gratin dish) and preheat oven to 375.

Slice potatoes (if you don't have leftover baked potatoes, you can cook them up in the microwave first) and arrange in bottom of baking dish.

Top potatoes with pepper and garlic.

Add chicken on top of potatoes, then layer on spinach leaves and panino slices.*

Add basil and bake for one hour or until chicken is fully cooked through.

During the last few minutes of cooking time, saute mushrooms in butter over medium heat.

Once mushrooms are browned, add a little garlic salt.

Top baked chicken with mushrooms and serve.

* Note -- I actually layered the spinach on top in my dish, but next time would layer under the cheese so the cheese browns better and the spinach doesn't burn.