1. Preheat oven to 400ºF; line a large rimmed baking sheet with foil and mist with cooking spray. Warm oil in a large skillet over high heat. Sprinkle pork with salt and pepper and cook, turning with tongs, until browned on all sides, 3 to 5 minutes total. Transfer to baking sheet and roast until an instant-read thermometer inserted into thickest part of meat registers 155ºF, 15 to 18 minutes. Transfer pork to a cutting board, tent with foil and let rest for 5 minutes.
2. Melt butter in same skillet (don't wash or wipe out skillet). Add apples and cook over medium-high heat, stirring often, until softened and beginning to brown, 5 to 7 minutes. Scrape into bowl, add onion and thyme to skillet, and sauté until softened, about 3 minutes. Pour in cider and cream and bring to a boil, stirring to incorporate browned bits on bottom of skillet. Cook, stirring frequently, until sauce thickens, about 5 minutes.
3. Return apples to skillet and heat through, stirring often. Season with salt and pepper. Slice pork and serve with sauce.