Preheat the oven to 425°F. Toss the carrots, parsnips, and beets with 2 Tbsp olive oil, the thyme, salt, and pepper. Spread on a sheet pan and roast 25-30 minutes, stirring halfway.
Meanwhile, pat the pork chops dry and season with salt and pepper. Heat 1 Tbsp olive oil in a cast iron skillet over medium-high heat. Sear the chops 3-4 minutes per side until golden, then remove and set aside.
Pour the apple cider into the skillet, scraping up the browned bits. Whisk in the Dijon and vinegar and simmer 5-6 minutes until reduced by half. Stir in the butter to finish the glaze.
Return the chops to the skillet, spoon the glaze over them, and cook 2-3 minutes until just cooked through (145°F internal temperature).
Serve the pork chops with the roasted veggies, drizzling extra glaze on top. Garnish with fresh thyme and apple slices.