1. Cream butter with sugar. Add eggs, one at a time, beating thoroughly after each addition. Mix in flour and nuts. Chill thoroughly, preferably overnight.
2. Shape mixture into bars about 3 inches long, 1 inch wide, and 1/2 inch thick. Brush with beaten egg. Arrange on greased cookie sheets.
3. Bake at 350°F 10 to 15 minutes. Cool cookies on wire rack