Preheat the oven to 400°F and cover a sheet pan with parchment paper.
Cut the squash in half and scoop out the seedy centers. Rub it with olive oil and sprinkle with salt. Cut a whole garlic bulb in half crosswise and rub it with more oil. Roast them face down for 40-50 minutes. Check on the garlic at the 30-minute mark and remove it if it's caramelized on the surface. Set it aside until it's cool enough to handle.
3 Tablespoons olive oil, 1 medium-large butternut squash, 1 whole head garlic
While it's cooling, heat remaining Tablespoon of olive oil in a large dutch oven or stock pot over medium heat. Add the onion and sweat until its translucent and starts to turn golden, 2-3 minutes.
1 medium yellow onion
Transfer the onion to a stand blender with the vegetable broth, maple syrup, nutmeg, cinnamon, salt, and pepper. Use a large spoon to scoop the butternut squash from the skin and add to the blender. Squeeze the roasted garlic into the blender.
3 cups low sodium vegetable broth, 1/4 cup pure maple syrup, 1/2 teaspoon ground nutmeg, 1 teaspoon ground cinnamon, 1 teaspoon sea salt, 1/4 teaspoon black pepper
Cover the blender tight and blend on high until smooth, 1-3 minutes. You can use the soup setting to heat the soup if you have one. If not, return the smooth soup to the pot and simmer over low to warm. Taste and add more salt, pepper, or cinnamon as needed.
Serve warm with crispy fried sage, heavy cream, crème fraîche, toasted pumpkin seeds, or more cinnamon.