Because you're going to blitz the soup, it doesn't really matter how you chop the onion, garlic, and chili pepper. Peel the onion and slice. Set aside for later. Peel the garlic and roughly chop. Set aside for later. Roughly chop the chili pepper. Set aside for later. Peel the potatoes and cut into chunks. Place in a bowl with water so the potatoes don't brown. Poke some holes all over the butternut squash and put it in the microwave for 2,5 minutes. This step is optional but it does help with the peeling later. Cut off the top and bottom and cut the squash in half crosswise. The bottom part that's wider has the seeds. Cut the bottom part in half and remove the seeds. Then peel the entire squash and cut into the same size as the potatoes. Set aside for later.
In a large pot, heat up a splash of water, vegetable broth, or oil. Then sauté the onion, garlic, and chili pepper for about 3 minutes or until the onion is soft and translucent. Add in more water/broth/oil if the pan gets too dry. Add in the curry powder and a splash of water/broth/oil and sauté for a minute. Then add the potatoes (drained from the water) and the butternut squash. Mix everything until all the ingredients are covered in the curry powder, then add in the vegetable broth.
Let this come to a boil. Once boiling, simmer for about 1 minutes or until the potatoes and butternut squash are easy to pierce with a fork. Take off the heat and blitz with an immersion blender until smooth. Put the soup back on the heat and taste and adjust.
Drizzle a little coconut milk on top, this is optional but highly recommended!