Preheat oven to 400°F (200°C) and line a baking sheet with parchment paper.
Cut the pumpkin in half, lengthwise. Use an ice cream scoop to scrape out the seeds and strings. Brush the inside of the pumpkin halves with a teaspoon of oil, and place the pumpkin halves cut-side down on the prepared baking sheet.
Bake for about 40 minutes, or until the flesh is tender. Remove from the oven and set aside.
Heat the oil in a deep saucepan over medium heat. Once hot, add the onion and garlic, and sauté for 3-5 minutes, or until golden brown. Add the salt, ground black pepper, cinnamon, nutmeg, maple syrup, and water.
Scoop out the flesh of the roasted pumpkin and add it to the pot as well. Let simmer for about 10 minutes.
Next, transfer to a blender. Add the soaked cashews and blend on high-speed for 10-20 seconds, or until smooth. Taste and adjust saltiness if needed. Transfer to a saucepan to reheat once ready to serve.