Preheat oven to 325. Line cookie sh sheets with parchment paper.
Whisk flour, baking soda and salt in a bowl to combine
In a large bowl beat butter and both sugars until light and fluffy, about 2 minutes
Add egg, egg yolk and vanilla and beat in
Add flour mixture and stir until well blended but not over mixed
Fold in broken candy bar pieces to incorporate candy among batter
Roll in 1 1/2 inch balls, place 2 inches apart on prepared cookie sheet.
Bake 12 to 15 minutes until light golden, they will be soft. Let cool on cookie sheet about 5 minutes until a spatula slides under them easily. Transfer to racks to cool completely, or of course you can also ear warm! After they cool they do freeze very well.
