Step 1

Take your roast chicken carcass and strip off any little bits of meat you can find. You may have to pull it to pieces to get the most meat from it. Wrap up the bits of meat and refrigerate for adding later. Put all the leftover bits of chicken in a large pan. Add the onion, carrots, salt and pepper and cover with water (at least 1.5litres). Bring it to the boil and let it simmer for 2-3 hours - until the stock looks a creamy brown colour and has reduced by at least a third. Turn off the heat and leave to cool slightly, then put a sieve over a large bowl, and empty everything into the sieve. Throw the sieve contents away. You should be left with approx. 800ml/3.5 cups of stock (if not, just top up with a bit of water).

Step 2

Heat half the butter in a large sauce pan. Add the onions and cook for 5-6 minutes, until they're soft and translucent. Add in the mushrooms and cook until they start to go golden brown. Add in the green chilli and garlic, cook for 1 minutes then add the rest of the butter. When the butter has melted, stir in the flour using a whisk and cook for 1 minute, stirring all the time. With the heat on medium-high, start to ladle in the chicken stock, stirring with the whisk all the time. When all the stock has been added, keep stirring until the soup thickens and bubbles gently. Turn the heat down to medium-low and add in the reserved chicken and cream. Stir, then add in the lemon juice. Have a taste to see if if needs a little more lemon juice or salt and pepper.

Step 3

Divide between three bowls and top with a few chopped spring onions and green chilli slices.