Please identify this tree in the Netherlands
I suspect this is a hazel (Corylus avellana) based on:


the leaves
the male flowers (not mature in your photo)
the fact that it is a common tree in Europe)


This one has twisty branches, so it could well be of a particular variety called "contorta".

According to 
https://en.wikipedia.org/wiki/Corylus_avellana#Cultivation_and_uses


  A selection with twisted branches has been propagated horticulturally as Corylus avellana 'Contorta'.