Preheat your oven to 400°F (200°C). Grease a large baking dish (like 9x13) with a little olive oil.

Properly season the chicken breasts with salt and pepper on both sides. In a small bowl, whisk together the high-quality balsamic vinegar, minced garlic, dried oregano, and dried basil. (Optional: reserve 2 tbsp of the marinade for later). Place the seasoned chicken breasts into a separate large bowl or reusable bag. Pour the balsamic marinade over the chicken, making sure each piece is coated. Let the chicken rest in the marinade for 20 to 30 minutes at room temperature (or up to 4 hours in the refrigerator).

Remove the chicken breasts from the marinade and place them in the prepared baking dish. You can drizzle some of the excess marinade over the chicken. If using green beans, toss them in a small bowl with 1 tablespoon of olive oil, salt, and pepper, then arrange them around the chicken in the baking dish. (Optional: drizzle green beans with the reserved marinade).

Bake the chicken in the preheated oven for 20 to 25 minutes, or until the internal temperature of the thickest part of the breast reaches 160°F (71°C) on a meat thermometer. If your chicken breasts are very thick, you may need an additional 5 minutes.

Carefully remove the baking dish from the oven. Arrange the mozzarella cheese slices (or shredded cheese) over the top of each chicken breast. Return the dish to the oven and bake for an additional 3 to 5 minutes, or until the mozzarella is completely melted and bubbly.

Remove the dish from the oven and let the chicken rest in the baking dish for 5 to 10 minutes. This critical step allows the internal juices to redistribute. After the resting period, slice the chicken breasts into medallions (as shown in the image). Serve the chicken slices over the green beans, and finish by drizzling the entire dish with your balsamic reduction/glaze and a generous sprinkle of fresh parsley and basil.