Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Halve the baby potatoes and trim the tough, woody ends off the asparagus spears.
Place the chicken breast, halved potatoes, and trimmed asparagus onto the prepared baking sheet.
Mince the garlic cloves and finely chop the fresh rosemary leaves.
Drizzle the olive oil over the chicken and vegetables, then sprinkle evenly with the minced garlic, chopped rosemary, sea salt, and black pepper.
Squeeze the juice from the half lemon over the entire tray, then place the remaining lemon rind on the pan to infuse more citrus aroma while roasting.
Toss the potatoes and asparagus with tongs to ensure they are well-coated in the oil and seasonings, and flip the chicken to coat both sides.
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 golden and fork-tender.