Remove the skin and seeds from the sweet pumpkin and cut it into small pieces.
Slice the onion thinly.
Heat olive oil in a pot and sauté the onions.
Add the sweet pumpkin and sauté together.
Pour in water and boil until the pumpkin becomes soft.
Blend all the ingredients until smooth in a blender.
Return the blended mixture to the pot, add milk, and bring it to a boil once more.
Season with salt and pepper to taste.