Peel and finely chop the onion and garlic.
Peel & dice the sweet potatoes.
Heat the in a pan, add the onion and rosemary leaves then fry for 3-5 minutes until soft. Add the garlic and chilli, stir for a minute.
Add the sweet potato cubes, stir for two or three minutes, then pour in the hot stock.
Bring it to the boil, then simmer over a low heat until tender (this will take about 20 minutes).
Liquidize or blend it with a hand-held blender until smooth and creamy. Taste and season to your liking.
Serve with blue cheese crumbled on top, if you like, or just with ground pepper.