Cut the butternut squash in half lengthways and scoop out the seeds with a spoon. Lightly score the flesh with a sharp knife and brush over a little oil with a sprinkle of salt and pepper. Place in a baking tray, skin side up.
Place the whole sweet potatoes on the baking tray next to the cut butternut squash.
Roast in the oven for 45-60 minutes until the flesh is soft. Take out and leave to cool.
Put a large pot on the hob on a medium heat. Add in the olive oil, onion, garlic, ginger and chillis. Cook until the onions have become translucent, you don't want to colour them.
Stir in the lemongrass and paprika.
Peel off the skins off of the sweet potatoes and roughly chop the flesh. Scoop out the flesh of the butternut squash and add to the pot along with the sweet potato.
Pour in the vegetable stock and coconut milk into the pot. Stir well, turn the heat to high and bring to the boil. Let the soup simmer, stirring occasionally, for 15 minutes.
Use an immersion blender or stand blender to blend the soup til smooth.
Notes
Let the sweet potatoes completely cool once they are roasted - they will be much easier to peel this way! Don't worry if small bits of skin are left as everything will get blended.
Take the time to finely slice and dice all the onions, garlic, ginger and chilies to really get the most of the flavours.
I prefer to use fresh garlic, ginger and chilies, but you can use pastes if they are more convenient.
I used my stand blender to blend the soup. Take care when transferring the soup from the pot to the blender as it will be piping hot. An immersion blender will also work well.
Make sure that the soup is cooled before refrigerating or freezing.
Nutritional values are based on one of eight servings and are an estimate only.