Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Slice the baby potatoes into halves and trim the woody ends off the asparagus spears.
Place the chicken breast, halved potatoes, and trimmed asparagus onto the prepared sheet pan.
Drizzle the olive oil over the chicken and vegetables, then sprinkle evenly with dried rosemary, thyme, garlic powder, sea salt, and black pepper.
Toss the vegetables and rub the chicken to ensure everything is thoroughly coated in the oil and spice mixture.
Arrange the ingredients in a single layer, placing the chicken in the center to ensure even cooking.
Squeeze the juice from the half lemon over the entire tray, then place the lemon hull on the pan to release aromatic oils during roasting.
Roast for 20 to 25 minutes until the chicken reaches an internal temperature of 165°F and the potatoes are fork-tender and golden.