Zucchini Chicken

I found this recipe on Recipezaar's website. We've had it a few times and it's delicious!

I medium onion, sliced
4 boneless skinless chicken breasts
1/2 tsp. salt
1/4 tsp. pepper
1/2 lb. fresh mushrooms (optional)
2 medium zucchini, sliced
2 garlic cloves, minced
1 (14 1/2 oz.) can of diced tomatoes (they say drained, but I didn't)
3/4 tsp. basil
1/2 tsp. oregano
1/4 cup parmesan cheese

Preheat oven to 450 degrees. Grease a 13x8 inch baking dish and place the sliced onions on the bottom. Place the chicken on top of the onions and sprinkle with salt and pepper. Layer mushrooms and zucchini over chicken. Combine garlic, tomatoes, basil and oregano, and pour over vegetables. Cover and bake for 30 minutes or until juices run clear in the chicken. Remove from oven and sprinkle with parmesan cheese!