Beat butter, sugar and vanilla.
Incorporate the egg and then the flour.
Mix well until a unified dough remains.
Cool the dough for 30 minutes or more. Preheat oven to 190 °.
Grind and flour two trays.
Place 1/4 cup granulated sugar in a bowl.
Use a spoon to make dough balls and go through the sugar.
Place the sugar side up, leaving space between the cookies.
Bake the cookies for 8 to 10 minutes, until the edges are lightly browned.
Cookies swell and become crunchy when cooled.
Remove the cookies from the oven.
Let stand in the pan for 5 minutes before moving them to a rack to cool completely.