Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.

Toss the butternut squash cubes with 1 tablespoon olive oil, a pinch of salt, and a pinch of black pepper. Spread them in a single layer on the baking sheet.

Roast for 25 to 30 minutes, flipping halfway through, until the squash is tender and lightly caramelized.

While the squash roasts, heat the remaining 1 tablespoon olive oil in a large pot over medium heat. Add the onion, carrot, and celery, and cook for 6 to 8 minutes until softened.

Stir in the garlic, cumin, cinnamon, and nutmeg. Cook for 1 minute until fragrant.

Add the roasted butternut squash, vegetable broth, water, 1 teaspoon salt, and 1/2 teaspoon black pepper to the pot. Bring to a boil, then reduce the heat and simmer for 10 minutes.

Use an immersion blender to puree the soup until smooth, or carefully blend in batches in a countertop blender.

Stir in the coconut milk, lemon juice, and maple syrup if using. Add more broth or water if needed to reach your desired consistency.

Taste and adjust seasoning with additional salt and pepper.

Serve warm, garnished with a swirl of coconut milk and pumpkin seeds or parsley if desired.