Wash and cut your delicata squash lengthwise and remove the seeds with a spoon. Place the squash cut side up on a baking tray.
Combine the olive oil and curry powder and brush the mixture all over the flesh of the squash.
Season with salt and pepper and roast it in the oven at 425 degrees for 35-40 minutes.
Let your squash cool for a few minutes, then gently scrape the flesh out of the skin with a spoon and set it aside in a bowl. (I discard the skin, however, note that it is completely edible, so if you get a couple of little bits in there when you are scraping out the roasted squash, it is plenty tender and won’t ruin the dish.)
In a large pot, melt the butter, add the onion and minced garlic and cook over med high heat for 3 minutes or until the onions are translucent.
Add in the coconut milk, fish sauce, red curry paste, brown sugar, turmeric, salt, pepper, cilantro and lime juice and whisk together well.
Add in your roasted squash and the four cups of chicken broth. Bring to a light boil, then reduce the heat and simmer for 20-25 minutes.
Remove from the heat and use an immersion blender to get the soup silky smooth, or put it in small batches through a blender. (If using a blender, be sure that you remove the lids center insert so the soup doesn’t explode and cover the blender with a towel while blending.)
Once the soup is smooth, return to medium-high heat and drizzle in the heavy cream while whisking.
Return to a simmer, then remove from the heat and serve with optional garnishes.