Heat the oven: Preheat to 425°F (220°C).
Lightly grease a baking dish large enough to hold the chicken in a single layer.
Prep the chicken: Pat the chicken breasts dry with paper towels. If they’re very thick on one side, pound them to an even thickness (about 3/4 inch) for even cooking.
Season simply: Sprinkle both sides with salt and black pepper. Set aside while you make the sauce.
Mix the glaze: In a bowl, whisk together Dijon mustard, whole grain/yellow mustard, honey, olive oil, minced garlic, smoked paprika, and lemon juice until smooth and glossy.
Coat the chicken: Spoon half the sauce over the chicken and rub to coat evenly.
Reserve the rest for basting.
Bake: Place the chicken in the prepared dish and bake for 15 minutes.
Baste: Pull the dish out and brush the remaining sauce over the chicken. Return to the oven and bake another 5–10 minutes, or until the thickest piece reaches 165°F (74°C).
Optional broil: For caramelized edges, broil for 1–2 minutes. Watch closely to avoid burning.
Rest and garnish: Let the chicken rest for 5 minutes so the juices settle.
Sprinkle with chopped parsley or thyme.
Serve: Pair with roasted veggies, steamed green beans, a crisp salad, or garlic mashed potatoes. Spoon any pan juices over the top.