2 cubes of soft butter
1 box sifted powdered sugar

2 eggs (one at a time and mix well)
1-1/2 tsp. peppermint extract
1 tsp. vanilla (or almond extract, or other flavoring)

1 (12 oz.) pkg. semi-sweet chocolate chips

Cool chips before adding to rest of mixture. Pour into buttered 9 x 13 inch pan and refrigerate.