01 - Preheat oven to 400°F. Lightly grease a baking dish large enough to accommodate chicken thighs in a single layer.
02 - Pat chicken thighs dry with paper towels. Season both sides generously 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 incorporated and smooth.
04 - Place seasoned chicken thighs in prepared baking dish, skin side facing up. Pour honey mustard sauce evenly over chicken, ensuring each piece is thoroughly coated.
05 - Bake uncovered for 30-35 minutes until chicken reaches internal temperature of 165°F and skin develops a deep golden caramelized color.
06 - For extra crispy skin, switch oven to broil setting for 2-3 minutes, watching carefully to prevent burning.
07 - Remove from oven and let chicken rest for 5 minutes. Spoon remaining pan juices over meat and garnish with fresh chopped parsley.