Preheat oven to 350 degrees F (175 degrees C). Grease baking sheets.
Beat butter and sugar with an electric mixer in a large bowl until creamy. Beat egg and vanilla extract into the butter mixture.
Sift flour, baking soda, and salt together in a separate bowl; stir into the butter mixture. Fold chopped candy bars into the mixture. Drop batter by the teaspoonful onto prepared baking sheets.
Bake in preheated oven until golden brown, 12 to 15 minutes. Cool on baking sheets for 5 minutes before transferring to cooling racks to cool completely.
