Combine softened butter, sugar, egg and sifted cake flour in a bowl in that order, and mix.

Wrap the dough in plastic wrap and let it sit in the fridge for at least an hour.

If you are making a chocolate version, use 115 g of cake flour and add 15 g of cocoa.

Roll the dough out to 4mm thick, and cut the cookies into whatever shapes you like. Bake for around 15 minutes in a 340F/170℃ oven.

For icebox cookies: After you have made the dough in Step 1, roll into a tube and chill in the freezer. After it has hardened, coat the outside in granulated sugar.

Cut the dough into 5 mm slices and line them up on a baking tray. Make a slight indentation in the middle. Bake for around 18 minutes in a 340F/170℃ oven.

They're done. I used a cat-shaped cutter, so I drew the faces on them with chocolate.

This is an icebox cookie version. They are simple and delicious.