Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Halve the baby potatoes and trim the tough, woody ends off the asparagus spears.
In a small bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, dried rosemary, sea salt, and black pepper.
Place the chicken breast, halved potatoes, and asparagus on the prepared sheet pan.
Pour the lemon-herb oil mixture over the chicken and vegetables, tossing them thoroughly to ensure everything is evenly coated.
Slice the half lemon into thin rounds and place them directly on top of the chicken breast.
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.
Remove from the oven and let the chicken rest for 5 minutes before serving to keep it juicy.