Combine 1/4 cup crushed candy and 1/4 cup powdered sugar in a shallow bowl. Set aside.
In a large bowl, combine butter, remaining crushed candy, remaining powdered sugar, and vanilla. Beat with an electric mixer on medium. Stir in flour and salt.
Form dough into 1-inch balls. Place on ungreased cookie sheets.
Bake at 325 for 12-15 minutes, until cookies are set but not browned.
Roll warm cookies in candy-sugar mixture. Cool on a wire rack. When cool, roll cookies in the candy-sugar mixture again.