Heat your oven to 220°C/Fan 200°C/Gas 7.
Slice the woody stem from your squash. Quarter it. Scoop out the seeds. Pop the squash on a baking tray. Season well. Slice your garlic bulb in half. Add to the tray. Roast on the top shelf of the oven for 30 mins or till golden and tender.
Scoop the roasted squash from the skin. Carefully squeeze out the roasted garlic cloves from their skins. Spoon both into a blender with the coconut milk (reserve 2-3 tbsp). Use a pestle and mortar to grind the cardamom pods. Discard the papery skins and add the ground seeds to the blender. Blitz till smooth.
Whizz in 250 ml stock (homemade or using half your stock cube), little by little, till the soup’s as thick or thin, rich or delicate as you like. Adjust the seasoning to taste.
Serve with a swirl of the reserved coconut milk, and a little extra dusting of ground cardamom seeds if you like.