Make the marinade by whisking together garlic, balsamic vinegar, olive oil, soy sauce, brown sugar, thyme, rosemary, and black pepper in a medium bowl. Pour into a large ziplock bag.
Rinse the chicken breast and pat dry, add to the ziplock bag, squish the bag around to coat all the chicken, squeeze out the air, seal, and refrigerate overnight.
Preheat your oven to 180 C (350 F). Line a baking sheet with foil and place a rack on the sheet. OR, and highly recommended, fire up your grill.
Remove the chicken from the marinade and shake off excess, discard marinade. Place chicken on the rack and bake for 10 minutes then turn over and bake for another 10 or until juices run clear. OR grill on the BBQ.
Let chicken rest for 5 minutes, serve with a side of your choice.