The recipe is based on the recipe from Nigella's How To Eat (a good book by the way).
125g plain flour (I used Italian 00)
15g-30g melted butter, cooled (optional)
Put the flour in a bowl, make a mound in the middle and add a pinch of salt. Crack the egg in and using a wooden spoon, mix it together, and then add in the milk in a steady stream. Mix with whisk and mix in the melted butter. When it is smooth, stop and leave the batter to rest for 30 minutes or overnight.