Chop up your onion and leeks and brown in your butter and garlic on the stove for 3 mins. Add your cauli and thyme. Add seasoning and xylitol.
Fry for about 5 minutes before adding stock and milk. Put on a lid and simmer for 20 minutes before turning stove off. I just left mine in the pot for the day and blended it when I got back from work but you can blend it straight away using a hand blender. If you're using a nutribullet allow it to cool slightly.
Taste test! Adjust flavours as desired. Serve with some buttery sourdough toast!