Preheat oven to 425° Fahrenheit. Pat chicken thighs completely dry with paper towels, then place chicken in casserole dish.
Liberally season all sides of chicken thighs with salt and pepper, to taste. Let chicken rest 15 minutes.
After 15 minutes, lightly brush olive oil over tops of chicken thighs. Place casserole dish in preheated oven and roast chicken thighs, uncovered, 30 minutes.
Toward end of 30-minute cook time, add cream of chicken soup and milk to medium bowl. Whisk ingredients together until well combined.
After 30-minute cook time is up, carefully remove casserole dish from oven. Pour cream of chicken soup mixture into casserole dish around chicken thighs, being careful to avoid pouring mixture directly onto chicken skins.
Return casserole dish to oven. Roast chicken thighs, uncovered, another 30 minutes. Check doneness of chicken thighs by piercing chicken with knife - when chicken is fully cooked, juices released after piercing will run clear.
When chicken thighs are fully cooked, remove casserole dish from oven. Serve chicken thighs warm with mashed potatoes or pasta and plenty of cream of chicken soup sauce.
Recipe Notes
Make it Dairy Free: Use unsweetened coconut milk or almond milk. You'll also want to use a dairy-free cream of chicken soup (store-bought if you can find one, homemade if not).
Make it Gluten Free: Use a gluten-free cream of chicken soup (again, store-bought if you can find one, or homemade if not).
Make it Keto: Use heavy cream instead of milk, and serve with palmini, zoodles, or mashed cauliflower.