Preheat the oven to 400°F (200°C).
In a mixing bowl, whisk together the honey, Dijon mustard, olive oil, minced garlic, salt, and black pepper until fully combined.
Place the chicken breasts in a baking dish and pour the honey mustard mixture over them, ensuring they are fully coated.
If using, sprinkle chopped rosemary over the chicken for added flavor.
Bake the chicken in the preheated oven for 25–30 minutes, or until the internal temperature reaches 165°F (75°C).
Remove the chicken from the oven and let it rest for 5 minutes before serving.
Serve the honey mustard chicken warm, drizzled with any remaining glaze from the baking dish.