Add the butter, oil and onions to a pan and fry until onions become soft and translucent. Add the mushrooms, garlic, dried parsley, fennel seeds, chilli flakes, salt and pepper. Stir well and leave to simmer for 5 minutes.
In a measuring jug, mix the stock cube with the water then add the stock to the pan along with the sweetcorn. Simmer for another 10 minutes then, pour into a bowl, make a coffee and grab some chunky bread to dip in the soup. I used cheese tiger loaf.