Pat dry and season. Blot chicken thighs dry with paper towels. Season all over with salt, pepper, garlic powder, and onion powder. Dry chicken browns better and gives you crisp skin and deep flavor.

Brown the chicken. Heat olive oil in a large skillet or braiser over medium-high. Place thighs skin-side down and cook undisturbed until deeply golden and crisp, about 7–9 minutes. Flip and cook 3–4 minutes more. Transfer to a plate; they’ll finish cooking in the sauce.

Sauté the aromatics. Pour off all but about 1 tablespoon of fat (leave the tasty bits). Add mushrooms and a pinch of salt. Cook, stirring occasionally, until they release moisture and start to brown, 6–8 minutes. Add shallot and cook 2 minutes, then stir in garlic, thyme, and smoked paprika for 30 seconds.

Deglaze the pan. Add chicken stock and scrape up any browned bits. Let it simmer for 2–3 minutes to reduce slightly. This concentrates flavor and sets up a silky sauce.

Make it creamy. Stir in cream and Dijon. If using Parmesan, add it now and stir until smooth. Taste and adjust salt and pepper. The sauce should be savory with a light tang from the mustard.

Return the chicken. Nestle thighs back into the pan, skin-side up, along with any juices. Reduce heat to medium-low, cover partially, and simmer 12–18 minutes until the chicken reaches 165°F at the thickest part. The sauce will thicken as it cooks.

Brighten and finish. Stir in lemon juice to lift the richness. If the sauce is too thick, add a splash of stock; if too thin, simmer uncovered for a couple minutes. Sprinkle with parsley.

Serve. Spoon mushrooms and sauce over the chicken. Pair with mashed potatoes, buttered noodles, rice, or toasted sourdough to catch every drop.