Warm 1 tsp olive oil in a medium pan over a low heat. Add the chicken. Gently fry for 5-6 mins till the chicken is browned all over. Turn once or twice while it cooks.
While the chicken cooks, peel and finely chop the onion. Peel and finely chop the carrot. Finely slice the celery. Halve the pepper. Scoop out the seeds and white bits, then roughly chop.
Add the onion, carrot, celery and pepper to the chicken. Season with a pinch of salt and pepper. Fry over a medium heat for 5 mins till the veg look soft and glossy. Stir every so often. If they stick, add a splash of water to loosen everything up.
While the veg cook, halve the squash and scoop out the seeds. Peel and chop it into small chunks. Peel and grate or crush the garlic. Stir the squash and garlic into the other veg.
Add a small pinch of cayenne pepper to the pan. Measure out 1 tsp each of the paprika, cumin and fennel seeds. Add to the pan. Cook and stir for 1 min.
Pour 700ml boiling water into the pan. Cover and bring to the boil, then turn the heat down. Simmer for 15 mins till the chicken is cooked through and the squash is soft. While the soup simmers, finely shred the cabbage.
Add the cabbage to the pan and stir. Simmer, without the lid on, for 4-5 mins till the cabbage is tender. Taste and add more salt, pepper, cayenne or paprika if you think it needs it. Ladle into warm bowls and serve straight away.