Cut a lid off each pumpkin, hollow out and dice the flesh.
Peel and finely chop the onions and garlic. Wash, halve, core and dice the peppers. Wash the chillies, slit open lengthwise, then remove the seeds and chop the flesh very finely.
Heat the oil in a large pan and sweat the onions and garlic until translucent. Add the mince and brown over a high heat, breaking it up to make sure it is browned all over. Season with salt and pepper.
Add the tomato puree, diced pumpkin, chilli and peppers. Fry briefly, then add the stock.
Add the chilli powder, cover and simmer over a low heat for about 30 minutes. Check the seasoning and serve in the 4 hollowed-out pumpkins.