Heat oil in a large heavy-bottomed pot over medium heat for 30 seconds or until the oil is shimmering. Add squash, onion, garlic, curry paste, cumin, salt, and red pepper flakes to the pot. Stir to combine.
Cook, stirring occasionally until onion is translucent. This stuff will start smelling AMAZING!!
Add broth. Bring the mixture to a boil, then reduce heat and simmer until squash is soft, about 15 to 20 minutes. You can taste and add more curry paste, salt or cumin to your liking.
Remove the soup from heat and let it cool slightly.
Working in batches, transfer the contents pan to a blender (do not fill your blender past the maximum fill line!). Securely fasten the lid (I like to use a kitchen towel to protect my hand from steam escaping from the top of the blender as I purée the mixture until smooth).
Transfer puréed soup to a serving bowl and repeat with remaining batches.
Stir the lime juice into the blended soup. Ladle soup into individual bowls. Use a spoon to drizzle coconut milk over each bowl, then lightly swirl the spoon through the topmost layer for a pretty design. Sprinkle some chopped cilantro on top, add a few crumbles of blue cheese (optional), and serve hot!