Whisk together the olive oil, lemon juice, garlic, honey, lemon zest, onion powder, 1 teaspoon of pepper, and salt. Add the chicken breasts to a large plastic bag and pound to make them even thickness. Add the marinade to the bag and gently massage into the chicken. Refrigerate for at least 30 minutes, but for the most flavor, 2-4 hours is ideal. Don't exceed 12 hours.
Before preheating the grill, transfer the chicken to a dish and top with remaining ½ teaspoon of cracked pepper and brush excess marinade over top. Allow to come to room temperature for even cooking.
Preheat your grill to medium high heat, about 400°F. Oil and clean before or after preheating (different schools of thought on this, but we do before). When grill is ready, place the chicken, presentation side down.
Cook the chicken breasts 6-8 minutes per side. If you go to flip the chicken and it doesn't pull away from the grill easily, allow it to cook another minute. The chicken is safe to eat at 165°F but it's best to pull off of the grill around 155°F-160°F. It will continue to cook off the grill as well.
Allow the chicken to rest for about 5 minutes before serving.
Store leftovers in an airtight container for 3-4 days or wrapped tightly in foil. You can also freeze leftovers. Allow to cool completely and then add to a freezer safe bag or container. Freeze for up to 2 months.