01 - Preheat your oven to 400°F. Grease a baking dish large enough to fit the chicken breasts in a single layer.
02 - In a medium bowl, whisk together the Dijon mustard, whole grain mustard, honey, olive oil, lemon juice, minced garlic, smoked paprika, thyme, salt, and pepper until smooth and well combined.
03 - Place the chicken breasts in the prepared baking dish. Pour the honey mustard sauce over the chicken, turning each breast to coat thoroughly on all sides.
04 - Bake, uncovered, for 30–35 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F. The sauce should be bubbling and slightly caramelized.
05 - For extra color and caramelization, broil on high for 2–3 minutes at the end, watching carefully to avoid burning the sauce.
06 - Remove from oven and let the chicken rest for 5 minutes. Spoon the remaining sauce over the chicken and garnish with fresh parsley before serving.