Preheat the oven to 400℉. Place the butternut squash on a baking sheet and season with salt and pepper. Bake in the oven for 15 minutes. Toss the butternut squash and bake for another 10 minutes. Set aside until you need it for the soup.
Heat a large pot with a tablespoon of canola oil over medium-high heat. Add the onion, garlic, and ginger and cook until the onions are translucent, about 5 minutes. Add the curry paste and mix together.
Add the vegetable broth and butternut squash. Bring to a boil. Reduce the heat and allow the soup to simmer for 15 minutes.
Transfer all the ingredients to a blender and blend until smooth.
Return the liquid to the pot. Add the coconut milk and heat up the soup. Season with salt and pepper to your liking. Serve in a bowl and top with scallions, cilantro, and a lime.