Mix the egg and the icing sugar in a small bowl.
Pour the butter, baking powder and flour in a big bowl, and grind it together with your fingers to make small crumbles.
Pour the egg mixture and the peanut butter in the flour mixture and work the dough together with a big spoon.
Place the dough in the fridge for one hour.
Start the oven at 180 degrees Celsius.
Spread flour on the surface you will roll out the dough approx four millimeters thick.
Use the cookie forms you like to form the cookies. Place the cookies on a baking paper.
Place the baking paper on a baking sheet and place the cookies in the middle of the oven for approx ten minutes.
Take out the cookies from the oven and let them cool down on the baking sheet.