Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Pat the skin-on chicken breast completely dry with a paper towel to ensure maximum crispiness.
In a small ramekin, whisk together the avocado oil, rosemary, thyme, garlic powder, sea salt, and black pepper.
Rub half of the herb oil mixture thoroughly over and under the skin of the chicken breast.
Toss the cubed sweet potatoes and halved Brussels sprouts in the remaining herb oil until evenly coated.
Arrange the chicken and vegetables in a single layer on the prepared baking sheet.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender.
Allow the chicken to rest for 5 minutes before slicing to ensure the juices stay locked in.