Preheat the oven to 200˚C, and line a roasting tray with greaseproof paper.
Top and tail the butternut, scoop out the middle membrane with seeds (hold onto these for great pepitas), and dice the butternut into 3cm/ 1½” sized pieces.
Place the diced butternut on the tray, pour over the melted butter, and scatter the brown sugar, salt, and pepper. Toss carefully, and spread evenly. Bake for 45mins, or until golden in colour and tender.
While the butternut is roasting, heat a stockpot our large saucepan over medium-high heat.
Dice the onion, and garlic, gently fry in olive oil until just golden.
Add the roasted butternut to the onion and garlic, mix and continue to cook for approx. 5mins. Pour in the stock, cover with a lid, and simmer for 10mins.
Remove from heat, allow to cool for 10mins, then process in either a blender or with a stick blender until completely smooth.
Serve with a swirl of cream, and some cut chives.