Heat oven to 350 degrees. In the large bowl of an electric mixer beat butter until creamy. Gradually add sugar and beat until light and fluffy. Add flour gradually and beat until well blended. Pat into an ungreased 15 1/2x10 1/2x 1 inch jelly-roll pan. Brush with egg. Sprinkle top with nuts. Bake 20 to 25 minutes or until golden brown. Watch carefully during final baking period, as cookies burn easily. Cool slightly until set, then cut with a sharp knife into strips, squares or diamonds and remove to a wire rack to cool completely. Makes about 30 1 1/2 x 2 1/4 inch cookies.