Combine the flour and eggs in a pan so that the lumps disappear.
In another pan, boil milk and sugar, do not forget to stir them.
Pour milk and sugar into a flour mixture with a thin stream, stir vigorously with a spatula. Put the cream on a small fire, stirring constantly, cook until thickened. Do not bring the cream to a boil.
After that, remove the eclair cream from the fire by adding vanilla sugar and butter to it. Mix well and then cool quickly by placing in ice or cold water.
Custard in milk turns out to be surprisingly tender, tasty and it will perfectly fit any cake, as well as custard cake. Preparing such a cream is not too difficult, it has an average density, during solidification, the cream becomes thicker.