Warm the oil and butter in a large saucepan over a medium heat. Add the onion, chicken and ham and slowly cook until onion is soft (do not let it brown).
Now pour in the stock, followed by the leeks, peas, oregano, garlic powder, 2 bay leaves and cinnamon. Stir, cover and simmer for about 20 to 30 minutes.
Take off heat, remove and discard bay leaves then blitz in food processor until smooth. You may have to do this in two parts depending on how much you have made. Pour back into a clean pan and place back on heat.
Add double cream and stir in. You may need to add water and further blitz to get desired consistency, I found a hand blender ideal to help me get it just right. Salt and pepper to taste. Then just simmer until hot through. Serve with a little cream swirled in and I like a little hot sauce dripped on mine.
For the stock
To make up the stock I use 2 Knorr® chicken stock pots dissolved in 600ml (1 pt) of boiling water, they are ace.