Preheat oven to 350°. Cream butter and sugars until light and fluffy, 5-7 minutes. Beat in egg whites. Beat in peanut butter and vanilla. In another bowl, combine flour, baking soda and salt; gradually beat into creamed mixture. Stir in candy bars.
Shape into 1-1/2-in. balls and place 2 in. apart on greased baking sheets. Bake until golden brown, 10-12 minutes. Remove to wire racks to cool.