Preheat oven to 275° Spray or grease 151/2 x 101/2 jelly roll pan. Into large bowl measure first 6 ingredients. With mixer on low speed, beat ingredients until well blended, occasionally scraping bowl with rubber spatula. Spread dough evenly in pan. Bake 1 hour and 10 minutes or until golden. About 10 minutes before cookies are done, in heavy 1 qt saucepan over low heat, heat chocolate pieces until melted, stirring frequently. Remove saucepan from heat. Remove jelly roll pan from oven; pour melted chocolate over baked layer in pan. With metal spatula, quickly and evenly spread chocolate over baked layer, sprinkle with peanuts, carefully pressing peanuts into chocolate. Immediately cut lengthwise into 4 strips, then cut each strip crosswise into 12 pieces. Cool in pan on wire rack until chocolate is firm. Store bars in tightly covered container. (abt 100 calories each)