Spatchcock your chicken (or in my house... get your handy neighborhood MashupDad to do it for you!).

Heat 1 Tsbp olive oil and 1 tablespoon butter in a 12" cast iron over medium high heat until butter is melted and oil is glistening hot.

Season both sides of your chicken generously with Kosher salt and black pepper.

Brown skin side down for 5-6 minutes until chicken is nicely browned and releases easily from pan, then flip and brown other side.

Turn off heat and squeeze lemon juice over chicken.

Arrange veggies in skillet around chicken.

Combine tarragon, mustard, and 2 tablespoon olive oil, then spoon over chicken and veggies.

Bake at 425 degrees for 35 minutes.

Top evenly with sliced mozzarella, then bake another 15 minutes or until cheese is browned and chicken reaches an internal temperature of 165 degrees. (If necessary, remove chicken from pan and roast veggies another few minutes until potatoes are cooked through -- I'd suggest cutting potatoes smaller than shown here so that they finish at the same time as chicken.)

Serve chicken and veggies topped with pan juices.