Prepare the honey mustard dressing by whisking all the ingredients together in a small bowl. You can skip this and use a bottle of honey mustard dressing if you prefer.
Place the chicken breasts between two layers of Saran wrap and tender them by hitting with a rolling pin or tenderizer until they are even and about 1cm thick.
Add 1/2 cup honey mustard to a big resealable bag with the chicken breasts. Place in the refrigerator to marinate.
Peel and chop the sweet potatoes into 1cm pieces. Chop onion into 1cm pieces. Add veggies to a sheet pan and drizzle with olive oil. Toss with the garlic powder, salt and pepper.
Bake at 200°C for 20 minutes.
Remove the chicken breasts from the honey mustard and discard any marinade. Nestle the chicken into the sweet potatoes. Don’t place on top of the vegetables.
Bake an additional 15-20 minutes until the chicken reaches an internal temperature of 73°C.
Remove from the oven and serve with additional honey mustard for dipping.
