Preheat the oven to 200°C.
Peel, halve and seed the butternut squashes. Cut into cubes of roughly 2x2 cm.
Peel and roughly chop the garlic, onion and celery. Arrange the butternut, garlic, onion and celery on a sheet pan and dress generously with the olive oil. Sprinkle on the Chinese Five-Spice, cinnamon and chopped thyme. Toss to coat evenly. Season well.
Roast until the butternut is tender and have a golden to deep brown color at the edges. The onions should be dark and roasted. This takes approximately 30 minutes. Toss halfway through to ensure an even roast. Remove from the oven.
In a large casserole, combine the roasted butternut and warm vegetable stock - make sure to scrape down every bit of roasted veg from the pan. Simmer for 8-10 minutes before removing from the heat.
In batches, place the soup in a thermo-resistant blender and process until completely smooth. Return to the casserole and stir in the butter and cream (optional). This will help make the soup appear glossy and creamy. Season with salt and pepper as necessary.
Serve piping hot and garnish with some fine biltong and fresh thyme.