Combine 1 teaspoon salt, ½ teaspoon ground black pepper, ½ teaspoon dried thyme, ¼ teaspoon dried sage, ¼ teaspoon ground allspice, ¼ teaspoon onion powder, and ¼ teaspoon garlic powder in a large bowl.
Thoroughly dry 2 pounds boneless, skinless chicken thighs by patting them with paper towels before adding them to the bowl with the spices. Toss until evenly coated in the rub.
Heat a large 14-inch skillet over medium heat. Add 2 tablespoons olive oil to the skillet.
Add the seasoned chicken thighs top-side down to the skillet. Cook for 5-7 minutes, until golden brown. Flip and cook for an additional 5-7 minutes, until the internal temperature of the chicken reaches 165 degrees Fahrenheit. Remove the chicken to a plate.
Add 1 tablespoon unsalted butter to the skillet. Once melted, add 2 large apples and spread them into an even layer. Cook for 2 minutes, until the apples are lightly browned before flipping them to cook the other side for another 2 minutes.
Add 1 ¾ cups fresh apple cider, ¼ cup chicken broth, and 1 teaspoon Dijon mustard to the skillet and bring to a simmer. Simmer for about 10 minutes until reduced by half. Taste and season with additional salt and pepper as needed.
Combine 1 tablespoon cornstarch with 2 tablespoons water in a small bowl before whisking it into the sauce. Once thickened, add the chicken thighs back to the skillet and cook for about 2 minutes until the chicken is heated through.
Spoon the sauce and the apples over the chicken before garnishing with fresh thyme or parsley and serving.
