Heat olive oil and butter in a saucepan over medium heat. Stir in onion; cook and stir until the onion has softened and turned translucent, about 5 minutes. Mix in brown sugar.
Finely chop ginger and garlic in a food processor. Add them to the onion mixture and cook, stirring frequently, until garlic is beginning to brown, about 10 minutes. Stir in the sage and cook for an additional 5 minutes.
Pour in apple juice and stir to loosen any browned bits in the pan. Add peanut butter, 1 tablespoon at a time, stirring well after each addition. Mix in chicken broth and squash.
Bring the mixture to a boil; reduce the heat and simmer, stirring frequently, for 5 minutes. Season the soup to taste with hot pepper sauce, Worcestershire sauce, and vinegar, tasting frequently until flavors are balanced. Simmer for 15 minutes. If the soup seems too thick, add water 1/2 cup at a time.
Remove the soup from the heat. Use an immersion blender to partially puree the mixture, leaving some of the onion intact. (If you don't have a handheld stick blender, carefully puree the hot soup in batches in a regular blender.) Pour in cream and blend to lighten the texture.
Ladle soup into warmed bowls and garnish with fresh-grated nutmeg and finely chopped pistachios.
You can use cooked butternut, acorn, or other winter squash. I use Tapatio® hot sauce and 4 to 6 cloves of garlic. You can substitute rice vinegar for the cider vinegar. To make this vegetarian- or vegan-friendly, use vegetable broth instead of chicken broth and unsweetened soy milk for the cream, if desired.
Other nice garnishes are decoratively sliced green onions, a sprinkle of cayenne pepper, or a dollop of creme fraiche.
Per Serving: 340 calories;25.1 g fat;
25 g carbohydrates;
8.4 g protein;
37 mg cholesterol;
461 mg sodium.