Pat dry chicken thighs with a paper towel and place them in a bowl.
Season the chicken thighs well on all sides with salt and pepper. Rub with Creole seasoning and set aside. You can do this an hour or two before to let it marinate.
Preheat the oven to 350℉ (180℃).
Heat the oil in an oven-proof cast-iron skillet over medium-high heat; place the chicken skin-side down. Cook for about 3 minutes, then flip them over and sear for another 3 minutes or until golden brown on both sides. Remove the chicken from the pan and set it aside on a plate.
Add the sliced onion, garlic, and thyme to the skillet, and stir for about 30 seconds. Be careful not to let it burn cause it might alter the flavor.
Whisk the mustard, honey, and chicken broth, and add it to the skillet. Deglaze the pan, scraping all that goodness (fond) off the bottom. Bring it to a boil, lower the heat, and simmer it for a minute or two.
Return the chicken thighs to the skillet and coat in sauce. Transfer the skillet to the oven and bake for 25-30 minutes, or until the chicken is cooked through. Thighs are juiciest if they reach an internal temperature of 175℉ (80℃).
Remove from the oven, plate, and serve with rice or potatoes and vegetables.