I have made 2 attempts today, beat the flour in to the water and butter and it makes a lovely dough, but as soon as I beat in the egg its runny and lumpy 
Not sure if the egg is too big so making it too runny or do I use the whole egg, I had it in my head that I only used the egg yolk but the recipie says use the whole egg.
Can anyone offer advice - other than buy one readymade elairs in tesco 