Turn on the oven and set it at 400°F/204°C.
Slice up the veggies while the oven heats up.
Lay the chicken breasts out on a baking sheet and salt and pepper both sides.
Lay the tomato slices out on the chicken.
Then the onions. and the garlic.
Sprinkle with salt and pepper then top it off with the lemon slices, grated parmesan and the rosemary. You could use dried rosemary if you would rather.
About ten minutes in the oven. When the juices run clear from the chicken or it reads 165°F on an instant read meat thermometer switch the oven to broiler and push the veggies off to the side of the pan.
Give it about 3-4 minutes under the broiler and serve up your Baked Chicken Breasts with Vegetables. This combo of the vegetables turned out to be a real tasty compliment to the chicken breasts.