Prep the chicken thighs and brush both sides with some olive oil and season with salt and pepper.
Add one slice of orange under the skin of each chicken thigh.
Then lay the chicken in the cast iron skillet and bake covered for about 45 minutes at 400 degrees.
For the Honey Orange Glaze
In a mixing bowl combine the melted butter, honey, orange marmalade, and mustard. (if using red pepper flakes-add them too)
Whisk until all is well combined and then remove pan from oven and uncover.
Then brush the chicken thighs with the honey orange glaze.
Place back in the oven and bake for an additional 20-30 minutes until chicken is cooked throughout and the skin is crispy. (Chicken should be at least 165 degree F)
Notes
**Cooking times may vary according to Oven and thickness of chicken thighs.