You will need
Preheat the oven to 240C/475F/Gas 9. Cut pumpkin (including skin) in 7cm/3in slices. Scoop out seeds using a large spoon.
Brush all over with 15ml/1tbsp olive oil and put in a roasting tray. Top with whole garlic cloves and thyme. Season generously and roast for about 45 minutes or until soft and caramelised.
Heat remaining oil in a large pan. Add sage, chopped garlic, onions, carrots and celery and cook for 10-15 minutes until soft but not brown.
Pour in stock, bring to the boil, season and simmer for 20 minutes until tender.
Leave pumpkin to cool. Remove flesh from skin (there should be about 1kg/2lb) and add to the stock. Simmer a further few minutes until pumpkin is beginning to break up.
Purée soup in a blender, add beans and warm through.