Heat a large 12-inch skillet over medium heat. I usually use a cast iron skillet, but any skillet this size works. You can also use a Dutch oven.
In a small bowl, mix together ¾ teaspoon salt, the coriander, cinnamon, nutmeg, dried thyme, and pepper. Sprinkle the spice mixture over both sides of the chicken thighs.
Add a drizzle of oil to the hot skillet, and swirl to coat. Add the chicken thighs to the pan. Cook for 5 minutes, then flip and cook for 5 more minutes or until cooked through (internal temperature should be at least 165°F (74°C)). Transfer chicken to a plate and cover lightly. You’ll add it back to the pan in the end of the next step.
Add the butter to the pan (no need to wipe it out first), and gently swirl to coat as it melts. Add the brown sugar, apples, and shallots, and sprinkle with the remaining ¼ teaspoon salt. Cook, stirring occasionally, until apples begin to soften, about 5 minutes. Pour in the apple cider and cook, stirring occasionally, until the cider sauce has slightly thickened, about 5 minutes. Add the chicken back to the pan and cook for 2 minutes.
Remove from heat. Spoon the apple mixture over the chicken to serve. Garnish with fresh thyme and rosemary, if desired.
Leftovers keep well in the refrigerator for a few days. The butter in the sauce will solidify, but once you reheat, it all comes back together. You can reheat on the stove over medium heat or in the microwave.