First, make your miso stock. Put 4 cups of water into a saucepan and heat to a simmer. Whisk the remaining 1/2 cup of water together with the miso, and pour that into the saucepan. Bring to a simmer, but don't let it boil.
Pour a few tablespoons of olive oil into the bottom of a large, heavy pot. When it's hot, add the onion and sweat it until it's translucent. Stir in the ginger, cumin, and cayenne, and toast spices for 30 seconds to 1 minute. Deglaze with a ladle-full of your miso stock.
Add the cubed butternut squash and the salt, mixing everything to combine, and then pour in the rest of the miso stock. Simmer until the squash is completely tender, about 20 minutes.
Turn off the heat, and purée the soup in a food processor or with a hand blender, being careful of the hot liquid. At this point you can strain for a super-smooth soup, or you can leave it how it is—up to you!
Return the puréed soup back to the pot, and stir in the coconut milk. Taste, adjust for seasoning and spice.
I have a thing for most foods topped with a fried egg, a strange disdain for overly soupy tomato sauce, and I can never make it home without ripping off the end of a newly-bought baguette. I like spoons very much.