Preheat a grill pan over medium heat on the stove top and spray with cooking spray.

Combine balsamic vinegar and olive oil in a bowl.

Season both sides of the chicken breasts with salt.

Place the chicken breasts on the preheated grill.

Brush the top sides of the chicken with the balsamic vinegar mixture.

Cook for 4-5 minutes and flip the chicken.

Brush with additional balsamic vinegar mixture and cook for an additional 4-5 minutes or until cooked through.

During the last 2 minutes of grilling, place 2 slices of mozzarella cheese over each chicken breast to melt.

In a large bowl, combine the diced roma tomatoes, sliced basil, minced garlic, salt, and balsamic vinegar.

Toss gently to combine the bruschetta mixture.

Place the grilled chicken breasts on a serving plate.

Top each chicken breast with the tomato mixture.

Serve warm.