Preheat the oven to 400 degrees F. Spray a baking dish with nonstick cooking spray.
Place about 5 slices of the polenta in an even layer on the bottom of the baking dish. Sprinkle with salt, pepper and 1 tablespoon olive oil. Place the chicken breasts on top of the polenta slices and sprinkle with salt and pepper. Top each with the Italian seasoning and Parmesan. Arrange the garlic cloves and tomatoes around the chicken. Sprinkle with salt and pepper and drizzle with the remaining 4 tablespoons olive oil.
Bake until the internal temperature registers 165 degrees F on an instant-read thermometer, about 30 minutes. Garnish with Parmesan and olive oil to taste. Serve warm.