Preheat the oven to 400 F.
Drizzle a little olive oil into a large cast iron skillet on medium heat. Wait for the oil to heat up.
Sear the chicken thighs on two sides for 5 minutes each. Remove to a plate.
Add the rest of the olive oil, the minced garlic, and the mustard greens to the pan. Saute for two minutes just to wilt the greens slightly.
Place the chicken thighs on top of the greens. Add the olives, cherry tomatoes, lemon juice, salt, and pepper.
Bake in the oven uncovered for 30 minutes. Halfway through, spoon some of the liquid over the greens to prevent any crisping.
Garnish with fresh parsley and enjoy!