Season the chicken. Pat the chicken thighs dry. In a small bowl, mix salt, pepper, garlic powder, onion powder, and paprika. Rub the seasoning all over the thighs, including under the skin where possible.

Brown the chicken. Heat 2 tablespoons oil in a large skillet over medium-high. Place thighs skin-side down and sear until the skin is deep golden and crisp, about 6–8 minutes. Flip and sear the other side for 3–4 minutes. Transfer to a plate; they won’t be cooked through yet.

Cook the onions low and slow. Reduce heat to medium. Add butter and remaining 1 tablespoon oil to the skillet. Add sliced onions and a pinch of salt. Cook, stirring often, until soft, golden, and jammy, 12–15 minutes. If they brown too fast, lower the heat and add a splash of water to deglaze.

Add aromatics. Stir in garlic and thyme. Cook until fragrant, about 30 seconds.

Build the gravy. Sprinkle flour over the onions and stir for 1 minute to cook off the raw taste. Slowly pour in chicken broth, stirring constantly to prevent lumps. Add Dijon and Worcestershire if using. Simmer until slightly thickened, 2–3 minutes.

Return the chicken to the pan. Nestle thighs into the onion gravy, skin-side up. Reduce heat to medium-low, cover loosely, and simmer until chicken reaches 175–185°F and is very tender, about 15–20 minutes. Uncover for the last 5 minutes to reduce the sauce if needed.

Finish with creaminess. Stir in heavy cream (or sour cream off the heat to prevent curdling). Taste and adjust salt and pepper. If the sauce needs brightness, add a small squeeze of lemon.

Serve. Spoon onions and gravy over the chicken. Garnish with fresh thyme. Pair with mashed potatoes, rice, or buttered egg noodles, plus a green like sautéed spinach or roasted broccoli.