DO-AHEAD TIP: Marinate chicken for at least 30 minutes or up to 6 hours.

In a small bowl, whisk together lemon juice and zest, 2 tablespoons of olive oil, salt and pepper; pour mixture over chicken then add thyme sprigs.

Rinse chicken breast halves under cool running water and pat dry with paper towels. Place them in a single layer between two sheets of plastic wrap and gently pound to 1/2 inch thickness.

Transfer to a large zipper-topped plastic bag and pour marinade over the top. Add thyme sprigs then seal bag and turn to coat; refrigerate for at least 30 minutes or up to 6 hours.

At time of cooking, heat remaining 1 tablespoon of olive oil in a large skillet over medium-high heat. Add chicken; cook for 4 to 5 minutes per side or until golden brown on the outsides and juices run clear.