Preheat oven to 375 degrees. Remove stem from pumpkin, and cut pumpkin in half. Scoop out pulp and seeds. Discard (or set aside if you want to keep the pumpkin seeds). Using a basting brush, rub olive oil across surface of pumpkin (use about ½ tablespoon total). Place halves on a baking sheet, cut sides up.
Bake about 1 hour, or until pumpkin is tender when pierced with a fork. Remove from oven, and let sit on baking sheet until cool enough to handle, about 10-15 minutes. Using a large spoon, remove pumpkin flesh and place in a food processor or blender. Purée until smooth. Set aside.
Heat 1/2 tablespoon olive oil over medium heat in a saucepan, and add onions. Cook until onions are soft and translucent. Add garlic, and cook for 30 seconds, stirring constantly so garlic doesn’t burn. Add puréed pumpkin, coconut milk, ginger, salt, and pepper. Bring to a boil. Lower to medium heat, and cook, uncovered, about 20 minutes.
To serve, sprinkle pumpkin seeds and/or pistachios across surface of soup.
Yield: 8 servings (serving size: about 3/4 cup)