Preheat oven to 300º. In
a large bowl, cream the
butter or margarine, sugars, and egg yolk with a mixer
until light and fluffy. In
another bowl, combine
flour, cinnamon, and salt.
Add to creamed mixture and continue beating just until blended. The dough will be stiff. Spread dough evenly in an ungreased 15-x-10-x-1-inch pan. Beat egg whites with a fork until foamy. Spread evenly on top of dough, sprinkle with nuts on top, and press in lightly. Bake 30 to 35 minutes. Cut into bars while still hot. Let cool in pan.