01 - Preheat the oven to 400°F. Lightly grease a baking dish large enough to hold all chicken thighs in a single layer.
02 - Pat the chicken thighs dry with paper towels. Season both sides with salt and black pepper.
03 - In a medium bowl, whisk together Dijon mustard, whole-grain mustard, honey, olive oil, lemon juice, minced garlic, smoked paprika, and rosemary until fully combined.
04 - Arrange the chicken thighs skin side up in the prepared baking dish. Pour the honey mustard sauce over the chicken, ensuring each piece is well coated.
05 - Bake uncovered for 30–35 minutes, or until the chicken is cooked through (internal temperature should reach 165°F) and the skin is golden and caramelized.
06 - For crispier skin, broil the chicken for an additional 2–3 minutes at the end of baking, watching closely to prevent burning.
07 - Remove from the oven and let rest for 5 minutes. Spoon extra sauce from the pan over the chicken. Garnish with chopped parsley before serving.