Cut the butter into small pieces and mix it with gluten-free flour, powdered sugar and egg in a bowl with the blender first and then by hand until a smooth dough. Put the dough around 30 minutes in the refrigerator.
Heat oven to 180 degrees. Roll out the dough on a bit of flour around 0.5 cm thick. Cut out as many cookies as you can using a cookie cutter. and place on the baking sheet. Bake in around 12-15 minutes. Before baking, you can smear cookies with beaten egg and sprinkle with chopped nuts.
Remove the cookies from the baking sheet and let cool.