Choose a new cookbook worth up to £28 when you subscribe to our magazine.
Soak the saffron strands in 4 tbsp hot water and leave on one side for about 30 mins until the liquid turns a deep auburn.
Heat oven to 200C/180C fan/gas 6. Soften the onions in 100g of the butter for 10-15 mins in a covered pan. Give them a stir now and again to stop them catching. Put the garlic and ginger in a small food processor with 3 tbsp water and blend to a paste. Add to the onions and fry for 2-3 mins. Stir in the spices, green chilli and lime juice.
Cut the top off the pumpkins and scrape out any seeds, leaving the flesh and skin intact. Transfer to a roasting tin and spoon the spiced onion mixture into the cavity of each pumpkin.
Put the lids back on the pumpkinscover with foil, and bake for about 1 hr 15 mins – until the flesh is tender when pierced with a knife. Leave to cool slightly. Turn oven down to 160C/140C fan/ gas 2. Scoop the filling and most of the pumpkin flesh into a pan, leaving a thin layer of flesh inside the skin. Stir in the Greek yogurt.
Wash the rice, then soak for 15 mins in enough cold water to cover. Drain, then partially cook the rice in a pan of fast-boiling water for 4-5 mins – it should still have bite to it. Drain in a colander.
Warm the spiced pumpkin mixture and layer it inside the pumpkin shells with most of the rice and a scattering of mint leaves. Finish with a layer of rice on top. Dot the top of the rice with the remaining 75g butter and drizzle each pumpkin with the saffron and soaking liquid.
Pour water into the base of the roasting tin to about 1cm depth. Put the lids on the pumpkins and cover with wet greaseproof paper, then seal the tin with foil. Bake for 1 hr – the rice should now be perfumed and perfectly cooked. Place the pumpkins on a serving plate, gently fluff up the rice with a fork and serve straight from the shells.