Add all the ingredients, except the butter, into a pot. Whisk.
Turn on the heat (low) and keep whisking. Then gradually add the butter.
Whisk until you get a creamy consistency.
For the cookies:
Preheat the oven at 180° C / 350° F.
Take the dough out of the fridge, one piece (130 gr) at a time.
Roll out to a thickness of half a cm on a floured surface or using two parchment paper sheets.
Cut into shapes using a cutter, and arrange the cookies on a baking tray, lined with parchment paper. Let chill in the fridge while you prepare the other cookies.
When your tray is full of cookies, bake the first batch for about 18-20 minutes.
To make thumbprint cookies: divide into 10 balls then gently press in the center of each ball, using your thumb or the rounded back of a teaspoon. Fill with raspberry jam.
Shape all the cookies and bake.
Garnish peppermint cookies:
Garnish with melted white chocolate and peppermint candy cane.
Ice cookies (easy icing):
Combine water and icing sugar until you obtain a thick "paste". Decorate.