Take chicken and generously spread Italian seasoning on all sides and underneath the skin. You can use more or less to your liking. I use my Italian seasoning recipe listed here: Place chicken in the oven and bake 30 minutes.
In a medium-large frying pan pour EVOO enough to cover pan in oil and heat on medium heat (around 5 out of 10). Add vegetables and mushrooms and saute until they are getting softer. Sprinkle with the same Italian seasoning mix about half way through.
Add the canned Italian tomatoes (juice and all) and continue to cook on medium heat until juice is about half way evaporated.
In a large baking dish (i use a 4 qt. dish) take sauce and use about half of it to line the bottom of the dish. Place the half cooked chicken on the sauce and use the remaining sauce to fill in the gaps between the chicken. You can prepare and make more or less sauce to your liking.
Stick back into oven at 420° for another 20-30 minutes or until done (I love using a digital meat thermometer with an alarm as opposed to cooking times anymore!) When there's about 5 minutes left, take out the dish and line the top of it with the sliced Swiss cheese and continue to bake until cheese is melted.
If you are watching your weight and wish to leave out the cheese, this dish is still very good! I wouldn't recommend it though. ;P
Let stand about 10-15 minutes and enjoy! It is good by itself as well as over riced of mashed potatoes.