1. Heat large saucepan over a medium high heat. Add the olive oil and butter and stir until the butter has melted.
2. Add the garlic and chilli peppers and stir for 30 seconds. Add the onions and stir.
3. Turn the temperature to low and cover the saucepan. Leave the onions to sweat for 10 minutes, stirring occasionally.
4. Add the pumpkin and stir. Cover again and leave to soften for 10 minutes, stirring occasionally.
5. Turn up the heat and add the vegetable stock. Bring to the boil, stir and then lower to a simmer. Cover and leave for 10 minutes, stirring occasionally.
6. Blend until smooth, stir in the Greek yogurt and add salt and pepper to taste.
7. Serve with toasted pumpkin seeds or a drizzle of Greek Yogurt.
Makes approximately two litres