Using a spoon, remove the seeds from the kabocha and peel the skin (Kabocha skin is edible, but we want to remove it this time). Cut the kabocha into wedges and set aside. Mince the onion to large sized dices. Heat butter in a pot and add in the minced onions. Stir and sauté the onions until the onions turn clear.
Add in kabocha, water, chicken bouillon, and sugar to the pot from Step 2. Simmer in low heat until the kabocha softens. Add in miso and stir well, dissolving the miso thoroughly.
Remove from the heat and pour the mixture to a blender or a mixer. Blend until smooth.
Pour the mixture back into the pot and cook in low heat. Add in milk and let it simmer while preventing the soup to boil over. The pumpkin soup is ready!
In a separate pot, boil plenty of water and cook the udon noodles for about 1 to 2 minutes. Once the noodles are cooked, rinse and drain. Place the noodles in a bowl.
Pour in plenty of pumpkin soup into the bowl. To finish, sprinkle on pumpkin seeds and thyme. Enjoy!