Preheat your oven to 400°F (200°C).
Prepare the pumpkin by cutting it in half and scooping out the seeds. Place the pumpkin halves cut-side up on a baking sheet.
Take the head of garlic and cut the top off to expose the individual cloves. Place the garlic head in the middle of one of the pumpkin halves.
Peel and slice the red onion into thick wedges, and peel and cut the carrots into large chunks. Arrange them around the pumpkin on the baking sheet.
If using fresh ginger, peel and finely chop or grate it. If using ginger powder, you will sprinkle it on later.
Drizzle olive oil generously over the pumpkin, garlic, onions, and carrots. Season everything with salt, black pepper, and a mixture of your chosen spices. Rub the spices in to coat the vegetables evenly.
Place fresh rosemary sprigs on top and around the vegetables. If using ginger powder, sprinkle it over the vegetables now. Roast in the preheated oven for about 45-60 minutes or until the vegetables are soft and caramelized. The exact time will depend on the size and thickness of the vegetables.
Once the vegetables are done, remove from the oven and let them cool slightly. Then scoop the pumpkin flesh from the skin and squeeze the garlic out of its skin. Transfer the roasted pumpkin, garlic, onions, carrots, and any juices from the roasting pan into a blender. Add the fresh parsley (save some for garnish).
Pour in the vegetable broth. Blend until smooth, adding more broth if necessary to reach your desired soup consistency. Taste and adjust the seasoning if needed. If you want a silkier texture, you can strain the soup through a sieve.
Reheat the blended soup in a pot if it has cooled down too much during blending. Serve the soup hot, topped with a generous sprinkle of vegan cheese, a garnish of fresh parsley, and a handful of toasted, chopped nuts for crunch.