Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Mince the garlic clove and finely chop the fresh rosemary leaves.
In a small bowl, whisk together 0.5 tablespoon of olive oil, the lemon juice, minced garlic, rosemary, sea salt, and black pepper.
Place the chicken breast on the prepared baking sheet and brush both sides thoroughly with the lemon-herb mixture.
Trim the woody ends off the asparagus and slice the carrots into thin rounds.
Toss the asparagus and carrots with the remaining 0.5 tablespoon of olive oil and a pinch of salt, then arrange them in a single layer around the chicken.
Place the two lemon slices on top of the chicken breast.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender.
Remove from the oven and let the chicken rest for 5 minutes before serving to ensure the juices redistribute.