01 - Pat chicken thighs dry thoroughly and season evenly with salt, black pepper, smoked paprika, and dried thyme.
02 - In a large skillet or Dutch oven, heat olive oil and unsalted butter over medium-high heat until shimmering. Place chicken thighs skin-side down and brown for about 6 minutes per side until golden. Transfer chicken to a plate and set aside.
03 - Add sliced onions to the pan and cook, stirring occasionally, until caramelized and golden, about 8 minutes. Stir in minced garlic and cook for 1 minute until fragrant.
04 - Evenly sprinkle flour over the onions. Stir continuously and cook for 1 to 2 minutes to remove the raw flour taste.
05 - Gradually pour in chicken broth while whisking to prevent lumps. Bring mixture to a gentle simmer, combining well.
06 - Return chicken thighs to the skillet, skin-side up. Spoon some gravy and onions over each piece of chicken.
07 - Cover pan and simmer on low heat for 25 to 30 minutes, or until chicken is fully cooked and the gravy is rich and thickened.
08 - Taste the gravy and adjust seasoning with additional salt or pepper if necessary.
09 - Transfer chicken thighs to serving plates, ladle with generous spoonfuls of onion gravy, and garnish with chopped parsley if desired.