Heat oven to 220°C (Gas Mark 7). Add 1 tablespoon of oil to a large, ovenproof pan and heat over high heat. Season the chicken thighs with salt and pepper, then add to the warm oil, skin-side down. Cook for 7 minutes, without turning, to brown well. Turn the heat down to medium-high, then stir in the onion and turn over the chicken. Cook for 5 minutes, until the onion has softened and is lightly browned. Add the tomato paste, garlic and half the thyme, and cook, stirring the paste into the onions, for 2 minutes, until fragrant and everything is nicely browned.

Add the stock, then add the spaghetti, stirring to submerge and evenly distribute. Use tongs to lift the chicken pieces so they sit on top of the spaghetti, skin-side up and add the olives. Bring to a simmer, cover with a lid and transfer to the oven for 30 minutes, until the liquid is absorbed.

While the pasta is in the oven, in a small bowl, mix together the Parmesan, breadcrumbs, parsley, lemon zest and remaining thyme. After 30 minutes, remove it from the oven and reset the temperature to a grill setting. Sprinkle the Parmesan breadcrumbs over the pasta and chicken, drizzle with the remaining oil and return to the oven for 3 to 4 minutes, until nicely browned and crisp. Leave to settle for about 5 minutes before serving warm, directly from the pan.