Cream butter , sugar and egg yolk together well. Mix in flour, cinnamon,vanilla and salt. Press dough{which will be stiff} into 9x 13 pan. Dough will be about 1/4 inch thick. Spread beaten egg white over top. Press nuts over top of that.  Bake at 400 for 5 minutes. Reduce temperature to 300 and bake for 25-30 minutes. Cut into squares to serve.