- Preheat oven to 425ºF. Remove top portion of pumpkin and slice in half. Scoop out and discard seeds. Slice into quarters. Place on baking sheet cut side up. Add tomatoes and onion. Drizzle with olive oil and roast for 40-45 minutes, turning vegetables halfway through cooking. Cool vegetables on baking sheet for 5 minutes.
- Scoop out pumpkin flesh and add into a blender or large pot with tomatoes, and onion. Add vegetable stock, 3 tablespoons soy sauce, heavy cream, thyme, basil and black pepper. Purée until smooth in the blender or use an immersion blender. Taste and add an additional tablespoon of soy sauce if desired.
- Heat soup over medium heat in a large pot until it reaches a low boil. Ladle into bowls and top with croutons and basil.