Step 1

Arrange a rack in the middle of the oven and heat the oven to 350°F.

Step 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.

Step 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.

Step 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.

Step 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.

Step 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.

Step 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.

Step 8

Bake uncovered until the chicken is cooked through and very tender, about 30 minutes. Meanwhile, coarsely chop 1/4 cup fresh parsley leaves.

Step 9

Transfer the chicken to a serving platter. Spoon the shallots, mushrooms, and sauce over the chicken and garnish with the parsley.