Preheat your oven to 400°F (200°C).
In a small bowl, whisk together maple syrup, Dijon mustard, olive oil, garlic powder, salt, and black pepper.
Place the chicken breasts in a baking dish and pour the marinade over them, ensuring they are well coated.
Spread the cubed sweet potatoes around the chicken in the same baking dish.
Roast in the oven for 25-30 minutes, or until the chicken is cooked through and the sweet potatoes are tender.
Baste the chicken with the pan juices halfway through cooking.
Once cooked, remove from the oven and let rest for 5-10 minutes before slicing.
Serve the chicken garnished with fresh thyme, alongside the roasted sweet potatoes.