Mix the butter with the icing sugar until the dough is fluffy and white.
Gradually, add the wheat flour and beat until everything is very smooth, in a consistent and soft dough.
Roll out your dough on film and take it to the freezer for 10 minutes, to get more consistent.
Remove the dough from the freezer and, with the help of a rolling pin, roll out the dough to a thickness of 0.5 cm. Then cut your cookies into the shape you prefer.
Place in a greased pan, cover with M&M's and bake at 180ºC, for 10 minutes.
Enjoy your cookies.