Peel the pumpkin and cut into 4cm cubes. Lightly toss in oil and roast at 180 degrees C in a baking tray until just tender.
Saute onion and celery in 1 tablespoon oil until transparent. Add chilli, ginger, garlic, cumin and ground coriander. Cook two minutes, then add the coconut milk. Take off the heat and add the chopped fresh coriander.
Pour the sauce over the pumpkin the baking tray, sprinkle with slivered almonds and bake a further 30 minutes. Serve with rice or couscous.