- Butternut squash, 2, about 4 lb (2 kg) total weight, peeled and cut into chunks
- Unsalted butter, 4 tablespoons (2 oz/60 g)
- Yellow onion, 1, chopped
- Ground cinnamon, ½ teaspoon
- Ginger, 2-inch (5-cm) piece, peeled and grated
- Salt and ground white pepper
- Ground nutmeg, 1/8 teaspoon
- Brown sugar, 1 tablespoon
- Vegetable broth, 4 cups (32 fl oz/1 l)
- Sour cream, ½ cup (4 oz/125 g)
- Fresh chives or flat-leaf (Italian) parsley, chopped, for garnish
In a frying pan over medium heat, melt the butter. Add the onion and sauté until softened, about 5 minutes. Add the ginger, cinnamon and nutmeg and sauté until fragrant, about 1 minute longer.
Put the squash chunks in the slow cooker and sprinkle with the brown sugar, ½ teaspoon salt and ¼ teaspoon white pepper. Pour the contents of the frying pan over the squash and add the broth. Cover and cook on the high-heat setting for 3 hours or the low-heat setting for 6 hours.
Using a blender or food processor, working in batches, process the squash mixture to a smooth purée. Return the soup to the slow cooker to keep warm until serving. Season to taste with salt and pepper. Ladle into bowls, garnish with a dollop of the sour cream and the chives, and serve.