To a large bowl, add the butter, the icing sugar, the flour, and knead until you have a homogeneous dough that is not sticky.
Line a baking dish with parchment paper. Roll out the dough with a rolling pin and cut it into rectangluar biscuits. Place the biscuits in the baking dish, spaced a little bit apart.
Bake in a preheated oven at 200° C for 10'-11' and remove the dish from the oven. Leave the biscuits to cool well so as not to crumble.