Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Slice the baby potatoes into halves and trim the woody, fibrous ends off the asparagus spears.
Finely mince the garlic clove and roughly chop the fresh rosemary leaves.
In a small bowl, whisk together the extra virgin olive oil, lemon juice, lemon zest, minced garlic, and chopped rosemary to create a bright herb marinade.
Place the halved potatoes on one side of the sheet pan, drizzle with one-third of the herb oil, and season with a pinch of the sea salt and black pepper.
Roast the potatoes in the oven for 12 minutes to give them a head start on becoming tender.
Remove the pan from the oven and place the chicken breast and asparagus spears on the remaining space.
Brush the remaining herb oil evenly over the chicken and asparagus, then season everything with the remaining salt and pepper.
Return the pan to the oven and roast for an additional 15 to 18 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are golden and crisp.