In a small Mixing Bowl, whisk together the 3 tbsp olive oil, 2 tbsp balsamic vinegar, 4 cloves garlic minced, 1 tsp dried Italian seasoning, 1 tsp smoked paprika, 1 tsp salt, ½ tsp black pepper freshly ground, and ½ tsp onion powder until well combined.

Place the 4 piece boneless skinless chicken breasts pounded to ¾-inch even thickness in a Ziploc Bag or shallow dish. Pour the marinade over the 4 piece boneless skinless chicken breasts pounded to ¾-inch even thickness, seal, and turn to coat evenly. Refrigerate for at least 1 hour and up to 8 hours. Remove from the Refrigerator 20–30 minutes before grilling to take the chill off.

Preheat your Grill to medium-high heat (about 425–450°F). Lightly oil the grill grates with a folded Paper Towel dipped in 3 tbsp olive oil, using Tongs. Remove the 4 piece boneless skinless chicken breasts pounded to ¾-inch even thickness from the marinade, letting any excess drip off.

Place the 4 piece boneless skinless chicken breasts pounded to ¾-inch even thickness on the hot Grill. Cook for 6–8 minutes on the first side without moving them, until grill marks form and the 4 piece boneless skinless chicken breasts pounded to ¾-inch even thickness releases easily. Flip and cook for another 6–8 minutes on the second side.

Use boneless, skinless breasts of even thickness. If over 1 inch thick, butterfly or pound to uniform thickness for faster, even cooking. Pat completely dry with paper towels — moisture kills a good sear. Season both sides generously with salt and pepper or your spice blend. Coat lightly with a high-heat oil (avocado or vegetable). Keep an Instant-Read Thermometer handy; target is 165°F.

Heat a heavy Skillet (cast iron or stainless) over medium-high. Add 1–2 tbsp high-heat oil and wait until it shimmers. Lay breasts away from you into the pan. Do not move them. Cook undisturbed 5–8 min on the first side until a deep golden-brown crust forms — if it resists lifting, it's not ready. Flip once and cook another 5–8 min. Drop heat to medium if the outside is browning too fast. Optional: add 1 tbsp butter in the last 2–3 min and baste. Total time: 10–16 min depending on thickness. Pull at 165°F internal temp.