Put the soften butter into a mixing bowl, then beat with a flat beater. When it gets creamy, add powdered sugar and salt, mix to combine.
Add the egg little by little, mix to combine.
Add the flour and mix them. Don’t over mix.
Divide the dough in two and wrap them up with plastic film, put the dough in the fridge at least 1 hour.
Roll the dough out until the thickness becomes around 1 to 1.2 inch/2.5 to 3cm.
Use your favorite shaped cookie cutters to cut out your cookies. Place them on an oven tray with baking sheet and bake at 170℃ 340℉ for 10-15 minutes.