Preheat your oven to 375°F (190°C) and lightly grease a baking dish or line it with parchment paper.
In a small bowl, whisk together the Dijon mustard, honey, olive oil, apple cider vinegar, garlic powder, salt, and pepper until the glaze is smooth and well-combined.
Place the chicken breasts in the prepared baking dish, and season them lightly with salt and pepper.
Pour the honey mustard glaze over the chicken, making sure the chicken is well-coated on all sides.
Bake for 25-30 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (74°C).
During the last 5 minutes of baking, you can baste the chicken with more glaze for an extra layer of flavor and a glossy finish.
Remove the chicken from the oven and let it rest for a few minutes before serving.
Garnish with chopped fresh parsley, if desired, and serve with your favorite sides.