Using electric beaters (or a mixer), beat the butter for a minute.
Add icing sugar and beat until incorporated and fluffy (about 1 minute).
Beat in the vanilla, then add the flour, cornstarch and salt and beat on low speed.
Once incorporated, beat on medium-high speed until the dough comes together.
Stir in Skor bits.
Shape the dough into 2 logs about 10" long (and about 1 1/2" across) and wrap tightly in plastic wrap & chill for at least 2 hours until firm.
Preheat oven to 325º F.
Grease or line 2 baking sheets with parchment paper.
Unwrap and slice the dough into cookies about 1/4" thick and arrange on baking sheet leaving at least 1/2" between them.
Bake for about 16 minutes, until the cookie barely starts to show a little color at the edges.
Cool cookies completely on baking sheet before removing.
Store in airtight container.
Can be frozen.