Whisk together Dijon mustard, honey, garlic, and salt in a small bowl. The ratio is key — taste it. It should be tangy-sweet. Adjust with more mustard or honey.
Pat chicken pieces dry with paper towels.
Place in a baking dish. Pour honey mustard mixture over and turn to coat each piece completely. Get it under the skin if using bone-in pieces.
Roast 25–30 minutes (boneless breast) or 35–40 minutes (bone-in thighs) until internal temperature reaches 165°F.
In the last 5 minutes, spoon the pan juices back over the chicken. This bastes it and deepens the glaze.