Prepare your butternut squash. I like to peel it, cut it lengthwise and remove the seeds, and then slice it into small cubes. Spread onto roasting pan and roast at 425 degrees for about 25 minutes until they start to brown. You can even roast frozen squash, it just takes a bit longer! Set aside.
While the squash is cooking, brown the ground turkey in a large pot. Drain and set aside.
In the same pot over medium heat, add the olive oil and heat. Add carrots, celery, garlic, peppers, and onion and saute for about 4 minutes until softened. If you are omitting the garlic and onion to keep this soup low FODMAP, you can use garlic-infused olive oil to add a bit more flavor.
Add all seasonings, fish sauce, the ground turkey, and broth. Allow to come to a simmer.
While the soup is simmering, put your butternut squash, choice of milk, and nutritional yeast into a blender and blend to desired consistency. This will make your soup a bit thicker. If you want to have bits of squash in your soup, simply put some in the soup and blend just a portion. If you do that, you may want to start with half the amount of milk and increase as needed.
Stir squash puree into simmering soup. Allow to come back up to a simmer and continue simmering for another 5-10 minutes. Optional: just before serving, add in a couple handfuls of spinach or kale to add a bit of green! You can also add black beans or lentils to make this soup a bit heartier.