In a medium bowl, whisk together the olive oil, lemon zest, lemon juice, minced garlic, fresh thyme leaves, chopped rosemary, salt, and pepper.
Add the chicken thighs to the bowl and turn to coat evenly with the marinade. Let them sit for at least 15 minutes, or up to 2 hours in the refrigerator for deeper flavor.
Trim the woody ends off the asparagus and toss the spears lightly with a drizzle of olive oil and a pinch of salt and pepper. Set aside.
Preheat your oven to 425°F (220°C). Place the marinated chicken thighs skin-side up on the sheet pan, spacing them out evenly. Arrange the asparagus spears around the chicken, ensuring they are not overcrowded.
Roast in the preheated oven for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the skin is golden and crispy. The asparagus should be tender but still crisp.
Optional: For extra crispy skin, switch the oven to broil and cook for an additional 2-3 minutes, watching carefully to prevent burning.
Transfer the chicken and asparagus to plates, spoon some of the pan juices over the top, and garnish with additional lemon slices or fresh herbs if desired. Serve and enjoy.