This is a blast from the days of my school dinners...it was one of my favourites.
35g (1.2 oz) plain flour
175g (6 oz) butter
1 teaspoon vanilla extract
100ml (3 1/2 fl oz) milk
175g (6 oz) light brown sugar
1 pastry case
Cube the butter and pop it in a pan with the sugar and milk. Heat over a medium to low heat until the butter has melted.
Add the vanilla extract.
Slowly add in the flour, whisking as you do.
Heat for about five minutes, whisking constantly until the mixture has thickened.
Pour into a pastry case and put in the fridge to set. It will only take about an hour.