Mix butter and sugar together until just incorporated. Do not over-mix at this stage, or the cookies may spread while baking. Add egg and vanilla and mix again on low speed.

Whisk flour and salt together in a medium bowl. Mix in butter and egg on low speed until dough has formed.

Chill the dough for 1 hour, then roll dough into slightly greater than 1/4 inch. Dust flour on surface if dough too sticky.

Cut out 2 inches round shaped and put on parchment paper. Roll reserved dough into small,marble sized balls for owl eyes and elongated shape for the beaks.

Mark a line as wings with using cookie cutter. Then, score cross with butter knife for mimic feathers on wings and dusting cocoa powder onto it.

Refrigerate cookies for 30 minutes to maintain crisp shape and bake in preheat 170°C oven for 15 to 20 minutes.