In a spacious mixing bowl, pour in the olive oil and add the minced garlic. Next, incorporate the freshly squeezed lemon juice and zest, followed by the dried oregano and thyme. Season generously with salt and freshly cracked pepper. Whisk the mixture until well combined to create a flavorful marinade.
Carefully add the chicken breasts to the bowl and ensure each breast is generously coated in the marinade. Cover the bowl with plastic wrap or a lid and let the chicken marinate in the refrigerator for a minimum of 30 minutes, but up to 2 hours if you desire a more intense flavor.
While the chicken marinates, preheat your grill or a large skillet to medium-high heat. Once heated, remove the chicken from the marinade, allowing any excess to drip off.
Place the chicken breasts on the grill or in the skillet. Cook each side for approximately 6–7 minutes, or until the internal temperature of the chicken reaches 165°F (75°C), ensuring the chicken is fully cooked and juicy.
During the last few minutes of the cooking process, evenly sprinkle the crumbled feta cheese, halved cherry tomatoes, and sliced kalamata olives over the cooking chicken. Allow these toppings to warm slightly and the feta to soften.
Once cooked, remove the chicken from the heat and let it rest on a cutting board for about 5 minutes. This resting period allows the juices to redistribute for optimal tenderness. Slice the chicken into thick pieces.
Serve the sliced chicken on a platter, drizzled with the remaining marinade from the bowl, and generously topped with freshly chopped parsley for a pop of color and flavor.