Roll the chicken thighs in the thyme or rosemary and sprinkle each side with a little salt and pepper.
Heat 1 tablespoon of butter a large pot over a low heat and fry the chicken on each side until lightly browned, approximately 10 minutes per side. Take the thighs out of the pan and set aside.
Melt another tablespoon of butter in the same pot and gently sweat the leek with a pinch of salt until soft, about 10 minutes. While the leek is cooking thinly slice the chicken thighs.
Pour the chicken broth into the same pot, bring to a gentle simmer, then put in the cabbage and carrots. Cover and cook for 20 minutes.
Stir in the kale, pumpkin and sliced chicken and cook for further 20 minutes, topping up with a little more broth or water if necessary.
Stir in the parsley and season the soup with salt and pepper to taste. Serve sprinkled with parmesan and a drizzle of olive oil.