Mix the butter with the icing sugar and the salt. Knead this till it’s an even mixture.
Then add the egg yolk and mix it for a minute.
After that add the flour and knead it till it’s an even dough. Once all the flour is incorporated directly stop mixing to prevent too much gluten from forming.
Now you can spread the dough on your desired mold. Level it and then bake the cookies at 175 °C for 10 to 15 minutes. You want a nice golden color.
Once golden take them out of the mold and let them cool down completely. Keep them covered for later.