Preheat oven to 220°C fan. Toss potatoes with 2 tbsp oil, salt, pepper. Spread on a large sheet pan. Roast 15 minutes.
Toss chicken with 2 tbsp oil, garlic, thyme, paprika, salt and pepper.
After 15 min, push potatoes to one side. Add chicken thighs skin-up to the pan. Add lemon halves cut-side down. Roast 20 min.
Toss broccolini with remaining oil, salt, pepper. Add to pan. Roast 5 more minutes.
Serve with the roasted lemons squeezed over.