Melt the butter in a pan add the onions and cook until they turn translucent

Add the mushrooms and cook for 5 mins

Take off the heat and add your flour and give a good stir

Add your stock little by little making sure you break down any lumps of flour until all the stock is added. Cook for 20mins on a low heat. Then purée down. Add some double cream and thyme and serve with buttery crusty bread