Step 1: Preheat your oven to 400°F (200°C). Toss the cubed butternut squash with 1 tablespoon of olive oil, salt, and pepper on a large baking sheet. Spread in a single layer.
Step 2: Roast the butternut squash for 25-30 minutes, or until fork-tender and lightly caramelized. This roasting step is crucial for developing the rich flavor of the butternut squash soup.
Step 3: While the squash is roasting, heat the remaining 1 tablespoon of olive oil in a large pot or Dutch oven over medium heat. Add the chopped onion and cook until softened and translucent, about 5-7 minutes.
Step 4: Add the minced garlic and grated ginger to the pot. Cook for another 1-2 minutes until fragrant, being careful not to burn the garlic.
Step 5: Stir in the roasted butternut squash, vegetable broth, cinnamon, and nutmeg. Bring the mixture to a simmer, then reduce heat to low, cover, and let it cook for 10 minutes to allow the flavors to meld for this butternut squash soup.
Step 6: Carefully transfer the soup in batches to a blender, or use an immersion blender directly in the pot. Blend until completely smooth and creamy. Be cautious when blending hot liquids.
Step 7: Return the smooth butternut squash soup to the pot (if using a regular blender). Stir in the heavy cream. Heat gently until warmed through, but do not boil.
Step 8: Taste the butternut squash soup and adjust seasonings as needed. Add more salt, pepper, or a pinch of sugar or maple syrup if desired to balance the sweetness.
Step 9: Ladle the creamy butternut squash soup into bowls. Garnish with toasted pumpkin seeds, fresh chives, or a swirl of crème fraîche, and serve hot.