Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Wash and halve the baby potatoes, then toss them on the baking sheet with half of the olive oil and a pinch of sea salt.
Roast the potatoes for 12 minutes to give them a head start.
While potatoes roast, mince the garlic and finely chop the fresh rosemary.
Season the chicken breast evenly with the minced garlic, rosemary, sea salt, and black pepper.
Remove the baking sheet from the oven, move the potatoes to one side, and place the chicken and trimmed asparagus on the other side.
Drizzle the remaining olive oil over the chicken and asparagus, then top the chicken with thin slices of lemon.
Return the pan to the oven and roast for 15 to 18 minutes, or until the chicken reaches an internal temperature of 165°F and the asparagus is tender-crisp.
Let the chicken rest for 5 minutes before serving to ensure it remains juicy.