Spritz a pan with Frylight and cook onion for a few minutes until softened.
Add Butternut and potato. Cook for a further 2 minutes.
Add garlic, salt and stock.
Cover and simmer for 30 minutes. Stir often.
Allow to cool for a few minutes. Then use a food processor or hand blender to blend until smooth.
This can also be made in a soup cooker. Throw everything in and set to smooth.