Take out the seeds and pulpy insides, peel the skin off the kabocha squash, and slice about 5 mm thick. Slice the onion thinly.
Heat up a pan over medium heat, add the butter and saute the onion. Take care not to let it burn by adjusting the heat.
When the onion is transparent, add the kabocha squash and saute briefly.
Add the water and stock cube, cover with a lid and simmer for about 10 minutes until the kabocha squash is falling apart.
Let it cool down a bit then put it in a blender and puree until smooth. Return to the pan.
There will be some left in the blender, so add a little milk, blend for about 3 seconds, then transfer to the pan to get everything.
Add the rest of the milk to the pan and mix well. Season with salt and pepper. When the soup comes to a boil, turn it off and cool the pan by putting it in water.
Chill the soup in the refrigerator. Pour into serving bowls. Drizzle a little cream on top, or scatter on some chopped parsley.
Story Behind this Recipe
Every summer my parents send us a big kabocha squash, but we have trouble using it all up. So I make lots of soup and chill it in the refrigerator. This is the sister recipe of the Lots Of Milk Carrot Soup (Recipe ID: 1290056).
If the kabocha squash is hard, microwave it whole for a few minutes and it will be much easier to cut. Be sure to put the squash in the blender after it's cooled down. If you have a stick blender, just blend it in the pan. It cuts down on dishes.