Step 1

Preheat oven to 400 degrees.

Step 2

Dry the chicken with paper towels and season both sides with Kosher salt and fresh ground black pepper.

Step 3

Heat 1 tablespoon oil in a large cast iron skillet over medium to medium-high heat. When the oil is shimmering and hot but not smoking, add the chicken, skin side down, and cook until well browned, about 8-10 minutes or until the skin is golden brown. Occasionally move the chicken around in the skillet to distribute the heat and avoid hot spots. Remove the chicken, skin side down to a rimmed baking sheet.

Step 4

Bake the chicken in the preheated 400 degree oven about 10 minutes then flip and continue to bake until the skin is crispy and the chicken is cooked through, about 5-8 minutes more. Transfer to a plate, tent with foil and keep warm. Reserve any juices in the pan for the sauce.

Step 5

While the chicken is in the oven, make the pan sauce. Pour out any excess oil from the skillet. Add the butter and olive oil and heat on medium-high until the butter is melted. Add the mushrooms and a pinch of salt. Cook over medium-high heat, stirring occasionally, until the mushrooms release their moisture and begin to turn golden, 6 to 8 minutes. Add shallots; cook and stir for 2 minutes. Add the garlic; cook and stir for 30 seconds. Season with salt and pepper. Carefully add the white wine; cook and stir scraping up any browned bits stuck to the bottom of the skillet. Cook until most of the wine is evaporated, about 2 minutes.

Step 6

Reduce the heat to medium and add 1 cup of chicken broth, thyme leaves, Dijon mustard and any accumulated juices from the baking pan. In a small bowl or measuring cup, stir together the flour and remaining 1/4 cup chicken broth. Add the slurry mixture to the pan and bring to a boil. Cook for about 3-5 minutes or until the sauce is thickened and slightly reduced. Reduce the heat to low and add the heavy cream if using. Place the chicken thighs in the skillet and nestle them down into the sauce. Cook for 2-3 minutes more or until warmed through. Drizzle the pan sauce over the chicken, if desired, and garnish with fresh thyme and plenty of black pepper.