Combine the olive oil, basil, and garlic together in a large zip lock bag. Add the trimmed chicken breasts and squish them around to evenly coat them. Seal and place in the refrigerator for 4-24 hours.
Prepare the caprese salad about 20 minutes prior to grilling the chicken. Combine the tomatoes, mozzarella, olive oil, vinegar, minced garlic, sea salt and freshy cracked pepper to taste together in a bowl. Toss until evenly combined. Chop and add the basil right before serving so it stays a vivid green. Side note: I liked using equal amounts of vinegar/oil in this recipe because I love the tang it gives to the salad; use less vinegar if you don't want it too tangy.
Heat a grill pan over medium heat; coat with cooking spray. Lightly season the chicken with sea salt and freshly cracked pepper, to taste. Once the pan is hot add the chicken and cook for 5-6 minutes or until golden brown. Flip the chicken over and continue cooking for 3-4 minutes or until the chicken has cooked through and the juices are running clear. Remove from the pan and let the meat rest for a few minutes. Place the chicken on a serving plate. Add the basil to the caprese salad and toss then spoon it over the center of the chicken breasts. Serve immediately. Enjoy.