Heat the oil in a large pot over medium heat. Add the onion and garlic, cooking until softened.
Stir in the ginger and turmeric, cooking for 1-2 minutes until fragrant.
Add the butternut squash cubes and stir well. Add the silken tofu, then pour in the broth or water, cover, and bring to a boil. Reduce the heat and let simmer for 20-25 minutes, or until the squash is tender.
Blend the soup until smooth using a hand blender or in batches in a blender. If you prefer a thinner consistency, add a bit more broth or water.
Season with salt and pepper to taste. Top with toasted pumpkin seeds for a satisfying crunch, if desired.