Instead of the butternut squash you can use any other pumpkin or squash in season. You can even use canned pumpkin and skip step 3.
For added flavor, roast your squash for 10 minutes in the oven drizzled with some olive oil. Then add the squash to the soup and blend as instructed.
Lemongrass can be found at most whole foods stores, or places that sell healthier options, such as health food stores. Walmart sometimes carries it as well.
If you don’t want to use lemongrass or try to find it, simply use two teaspoons of lemon zest in its place.
To thicken the soup, you can use a cornstarch slurry. Add a tablespoon of cornstarch with two to three tablespoons of the soup in a cup. Stir well before adding back to the soup. Allow to simmer a while longer until thickened a bit more.
Store in an airtight container, once cool, in the fridge, for four to five days. Store in the freezer for two to three months in an airtight container.