Instructions

1. Arrange a rack in the middle of the oven and heat the oven to 350°F.
2. Quarter 1 pound cremini mushrooms with the stems attached. Peel 8 ounces shallots, trim the ends, and cut in half lengthwise. Mince 3 garlic cloves.
3. Place 1/2 cup all-purpose flour on a plate. Season 8 bone-in, skin-on chicken thighs all over with 1 1/2 teaspoons of the kosher salt and 1/2 teaspoon black pepper.
4. Heat 1 tablespoon olive oil in a 12-inch or larger cast iron or oven-safe skillet over medium-high heat until shimmering. Meanwhile, dredge the chicken in the flour, shake off any excess, and place on a baking sheet or cutting board. Working in two batches, add the chicken skin-side down and cook until golden brown, 7 to 9 minutes. Flip the chicken and cook until golden brown on the second side, 3 to 4 minutes more. Return the chicken to the same baking sheet.
5. Add the shallots, mushrooms, and remaining 1/2 teaspoon kosher salt to the skillet. Cook, stirring occasionally, until the shallots are softened and the mushrooms release their liquid, 8 to 10 minutes. Add the garlic and cook for 1 minute more.
6. Pour in 1 cup dry white wine and scrape up any browned bits at the bottom of the pan with a wooden spoon. Simmer until the liquid is reduced by half, about 5 minutes. Add 1/2 cup low-sodium chicken broth, 2 tablespoons Dijon mustard, and 1 tablespoon whole grain mustard, and whisk to combine. Bring to a boil.
7. Remove the pan from the heat. Return the chicken skin-side up to the pan, nestling it into the shallots and mushrooms. Pour in any accumulated juices from the chicken.
8. Bake uncovered until the chicken is cooked through and very tender, about 30 minutes. Meanwhile, coarsely chop 1/4 cup fresh parsley leaves.
9. Transfer the chicken to a serving platter. Spoon the shallots, mushrooms, and sauce over the chicken and garnish with the parsley.