Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Slice the baby potatoes into halves and place them on the pan, tossing with 0.5 tbsp olive oil and a pinch of the salt and pepper.
Roast the potatoes for 10 minutes to give them a head start on crisping.
While potatoes roast, mince the garlic and combine it in a small bowl with the remaining olive oil, rosemary, thyme, salt, and pepper.
Rub the herb mixture evenly over the chicken breast.
Remove the pan from the oven, move the potatoes to one side, and place the chicken and the lemon half (cut-side down) on the pan.
Return to the oven for 10 minutes.
Add the asparagus spears to the pan, tossing them quickly in the pan juices, and roast everything for a final 8-10 minutes until the chicken reaches an internal temperature of 165°F.
Squeeze the juice from the roasted lemon over the chicken and vegetables before serving.