Preheat the oven to 400 degrees F., and line a half-sheet pan with parchment paper or a silicone mat.
Place the cubed pumpkin, sweet potato, sliced onion, and garlic on the baking sheet. Sprinkle with salt, cumin, and coriander. Mix well until everything is evenly coated with the spices.
Drizzle the oil and mix well. Place all of the ingredients in an even layer and place the garlic head cut side up. Drizzle some oil directly into the cut side.
Roast for 30 to 40 minutes or until some of the onions and garlic are beginning to char lightly.
Remove the baking sheet from the oven and place the roasted vegetables in a large pot with a lid. Place the garlic head on a plate to cool.
Pour 4 to 5 cups of water and add the bouillon cubes. Mix, bring to a boil, cover with the lid, lower the heat to a simmer, and cook for 30 minutes.
In the cup of a blender or food processor, place the silken tofu and squeeze the garlic out of the skin. Blend until smooth and set aside.
Take off the lid and stir while lightly mashing some of the soft pumpkin and sweet potato. Taste and adjust seasoning levels.
Turn off the heat and pour the tofu garlic mixture into the soup. Mix and serve.
Optionally garnish with fresh thyme and pumpkin seeds.
Notes
Roast properly: The veg should be properly caramelized/ a little charred for maximum flavor. Optionally, broil them at the end.
Use the best pumpkin: Skip the leftover carving pumpkins. Make sure to use a sugar pie pumpkin or other culinary variety for the best flavor.
Adjust the consistency/texture: You can blend some or all of the soup and optionally add extra broth for a thinner consistency.