Prepare the Sauce:
In a saucepan, combine all sauce ingredients: apricot jam, diced onions, soy sauce, honey, Dijon mustard, apple cider vinegar, minced garlic, ground ginger, and red pepper flakes (if using).
Heat over medium heat, stirring occasionally, until the jam has melted and the sauce is heated through.
Prepare the Chicken:
Preheat your oven to 375°F (190°C).
Trim any excess fat or skin from the chicken thighs.
Place the chicken thighs in a lightly greased baking dish and sprinkle them lightly with salt and pepper.
Bake the Chicken:
Pour the prepared apricot sauce over the chicken thighs, ensuring they are well coated.
Place the baking dish in the preheated oven and bake uncovered for 20 minutes.
After 20 minutes, baste the chicken thighs by spooning the sauce from the pan over each thigh.
Return the chicken to the oven and bake for an additional 20-25 minutes, or until the chicken is cooked through and the tops are just beginning to brown.
Serve:
Remove the chicken from the oven and let it rest for 5 minutes before serving.
Garnish with freshly chopped parsley, if desired.
Skim any grease off the remaining sauce in the pan and serve the sauce on the side.