Preheat oven to 400°F.
Preheat a cast-iron skillet over medium-high heat. Add half a turn of the pan of oil and the bacon; render then remove to plate. Add leeks to bacon drippings and wilt; add apples and toss to coat. Season with salt, pepper, nutmeg, sage and light brown sugar; cook to soften, 7-8 minutes, turning frequently. Add lemon zest and juice then remove apples to a serving bowl, add bacon and toss; cover with foil to keep warm.
Add another turn of the pan of oil. Season chops with salt, pepper and fennel. Brown on both sides and edges then add brandy to deglaze. Transfer pan to the oven, let brandy evaporate then add cider and roast 10-12 minutes more.
Remove chops to a platter and place pan with juices over high heat. Add crushed garlic, thyme and butter. Swirl sauce for a minute then spoon over chops. Serve with apples and bacon alongside.