1) Melt the butter with the flour in a medium saucepan. Pour in the milk then, using a balloon whisk, whisk everything vigorously together over a medium heat.
2) As soon as it comes to simmering point and it has thickened, turn the heat right down to its lowest setting.
3) Stir in the sugar and let the sauce cook for 10 minutes.
4) Add the brandy and the cream.
5) Pour the hot sauce into a jug and serve.
The brandy sauce can be made in advance and it will last up to 5 days in the fridge.
It can be reheated on low on the hob, stirring constantly. It can also be placed in a microwave container and heated on full power for 45 seconds, stir and then heat for a further minute. Leave to stand for 2 minutes before serving.
If you are making it in advance, lay cling film flat on top of the sauce when cooling. The cling film becomes the skin and no skin will be produced by the sauce. This will make the sauce smoother when you come to heat it up.