Preheat your oven to 204 °C (200 C) and line a large rimmed baking sheet with parchment paper.

Toss the cubed butternut squash with 15 ml of olive oil, kosher salt, and black pepper directly on the baking sheet, then spread into a single, even layer.

Roast in the oven for 30 to 35 minutes, turning halfway through, until the squash is tender and the edges turn deep golden brown.

While the squash roasts, heat the remaining 15 ml of olive oil in a large Dutch oven or pot over medium heat. Add the diced onion and cook for 5 minutes until soft and translucent, then add the minced garlic and cook for 1 minute until fragrant.

Transfer the roasted butternut squash into the pot with the aromatics. Pour in the vegetable broth, bring to a gentle boil, then lower heat to maintain a simmer for 10 minutes.

Remove the pot from the heat. Puree the mixture with an immersion blender until completely smooth. If using a countertop blender, blend in batches with the lid vented to allow steam to escape.

Return the pureed soup to low heat. Stir in the heavy cream, maple syrup, and ground nutmeg, warming through for 2 minutes before adjusting seasoning with additional salt and pepper.