Chop the onion and garlic. Cook in a large pot on low heat until onion is soft and translucent. I add salt to draw out some of the moisture and some oil so it doesn't stick. Chop and peel the carrot and celery and cook for about 10 minutes until soft.
Chop and skin pumpkin and put into the pot, along with the broth. You'll want the vegetables to be mostly covered, add some more if needed. Cook on low until the pumpkin is soft and then blend until smooth. Season with salt and pepper.
To make the parsley sauce, roughly chop the parsley with the stalks too and put in a mortar and pestle with a big pinch of salt and a glove of garlic. Pound until it is a paste and then add the olive oil. You want the oil to cover the parsley!
Serve the soup with the parsley sauce on top and some bread.
The parsley sauce will keep for up to a week in the fridge, as long as it is submerged in olive oil. You can also eat it with eggs, fish, meat, roast vegetables.

I like to make plain pumpkin soup but you want to make sure you use a butternut pumpkin or another sweet variety. What I have learnt when making soups is that you want the vegetables to be as fresh as possible because it will taste better, even though it is temping to use the old vegetables in the fridge. If you are vegetarian, use vegetable stock Leeks also go well in this soup instead of onion, if you have them. I also use butter to cook with the onion and garlic but just olive oil is nice too.