Preheat the oven to 400°F. Line a baking dish or rimmed sheet with foil for easy cleanup.

Pat chicken dry and season both sides with kosher salt and black pepper.

Whisk olive oil, lemon juice, lemon zest, minced garlic, Dijon mustard, thyme, and rosemary in a bowl. Spoon half the mixture over the chicken, flipping to coat. Let sit at room temperature for 10 to 15 minutes or refrigerate up to 2 hours.

Arrange breasts in the prepared dish and pour remaining dressing over the top. Bake for 18 to 25 minutes, depending on thickness, until an instant-read thermometer inserted into the thickest part reads 165°F.

Remove from oven and let rest for 5 minutes before slicing to keep juices locked in.

Combine the marinade as above. Pat chicken dry and season with salt and pepper. Coat breasts in the marinade.

Heat a large skillet over medium-high heat with 1 tbsp olive oil. When hot, add chicken and cook for 4 to 6 minutes without moving for a good sear.

Flip and cook another 4 to 6 minutes until the internal temperature reaches 165°F. If breasts are thick, lower heat to medium, cover, and cook a few extra minutes as needed.

Remove from pan and let rest for 5 minutes. Spoon any pan juices and a little extra lemon juice over the top before serving.