Preheat oven to 375°F (190°C) with convection fan on. If your oven does not have convection, you can increase temperature to 400°F / 200°C.
Heat a large sauté pan over medium-high heat. Add oil. Season chicken thighs with salt and pepper, on both sides. When pan is hot, place chicken thighs in the pan, skin side down.
Cook undisturbed, until skin is golden brown, about 5 minutes. Remove from heat and set aside. (*see note)
Line a sheet pan with parchment paper. Place garlic cloves, rosemary and lemon, on the sheet pan. Transfer chicken to sheet pan, skin side up, placing it on top of the lemon, garlic, and rosemary.
Roast for 30-35 minutes, until chicken is cooked through and skin is golden brown and crispy.
Remove from oven, and sprinkle with chopped rosemary and lemon zest while warm, if desired.