Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish.
Pat pork chops dry. Season all over with 1 tsp salt, pepper, and thyme.
Heat olive oil in a large skillet over medium-high. Sear chops 2–3 minutes per side until browned. Set aside.
Toss sliced apples and onions with brown sugar, cinnamon, a pinch of salt, and lemon juice. Spread evenly in the baking dish.
Whisk apple cider, Dijon, garlic, and melted butter. Pour half over the apple-onion layer.
Nestle the seared pork chops on top of the apples. Drizzle remaining cider mixture around the chops.
Cover tightly with foil and bake 20 minutes.
Uncover, baste with pan juices, and continue baking 20–25 minutes, until chops reach 145°F in the center.
Rest 5–10 minutes. Spoon the apple-onion juices over the chops to serve.