Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Halve the baby potatoes and trim the tough, woody ends off the asparagus spears.
In a small bowl, whisk together the olive oil, lemon juice, dried rosemary, garlic powder, sea salt, and black pepper.
Place the chicken breast, halved potatoes, and asparagus on the prepared baking sheet.
Drizzle the lemon-herb oil mixture over the chicken and vegetables, tossing them gently to ensure everything is evenly coated.
Place the lemon slice on top of the chicken breast for extra flavor infusion.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are fork-tender.