Preheat oven to 425˚F.
Lightly grease a 9x13 baking dish with cooking spray.
Arrange the cut tomatoes and red onions on the bottom of the baking dish; season with salt, pepper, and dried basil. Stir and set aside.
Drizzle olive oil over the chicken breasts and season them with salt, pepper, basil, and oregano.
Take the minced garlic with your fingers and rub it all over each chicken breast, rubbing in the seasonings at the same time.
Arrange the chicken over the tomatoes and set aside.
In a small mixing bowl, combine balsamic vinegar and sweetener; whisk until well incorporated.
Drizzle the balsamic vinegar over the chicken and tomatoes; flip the chicken over to coat all around.
Bake for 23 to 25 minutes or until done. Depending on the thickness of your chicken, it may need less or more time to cook through.
Remove from oven and add shredded cheese over each chicken breast.
Continue to bake for 3 to 4 minutes or until the cheese is melted.
Remove from oven and let stand 5 minutes.
Drizzle the pan sauce over the chicken, garnish with basil, and serve.