Sand cookies

Last week around this time, I was making cookies to take to our little EST meeting the next day. As I made a small mistake, I didn't have time to blog the recipe so here goes...
This is what you need:

• 125g flour
• 80g butter
• 50g powdered sugar
• 10g vanilla sugar
• A pinch of salt
  
• 1 egg yolk (optional)
• Little bit of crystal sugar (optional)
  

Put the flour in a bowl, cut the butter in little pieces and add to the flour. Then add the powdered, vanilla sugar & a pinch of salt. Kneed it to a firm dough. It will need lots of kneeding so that it all sticks together.
Roll it, put it in plastic foil and put in the refrigerator for 30 minutes.
Then unroll the dough. It needs to be plus minus a centimeter thick.
Press with cookie cutters some shapes out of the dough.
This is optional. It gives the cookies a nice brown, yummy crust but I found that it also deforms the shape of the cookies while baking.
Put the sides of the cookies into the egg yolk and then put it in the sugar.
Put all the cookies on a tray and make sure you leave enough room.
Put in a preheated oven for 15 minutes at 180 °C
Tada! :) Enjoy!