Melt butter in a large bowl.

Add sugars, salt, and vanilla to butter.

Mix until smooth and shiny.

Beat in egg.

Whisk together baking powder and flour.

Stir flour into butter mixture.

Carefully mix candy bar pieces into dough.

Roll dough into 16 equal balls and place on a greased baking sheet at least 1 inch apart.

Gently press dough to flatten slightly.

Cover baking sheets and refrigerate cookies overnight.

The next day, preheat oven to 375 degrees.

Bake cookies for about 15 minutes or until browned around the edges and on the bottom.

Let cookies cool on pan for 5 minutes, then transfer to a cooling rack.

Allow cookies to cool, then serve right away or store in an airtight container.