My grandmother used to make these cookies when we were children.The walnuts and cinnamon taste great together.
Preheat oven to 350r. Cream butter and sugar until light and fluffy. Add egg yolk to blend. Add flour and cinnamon. Mix until dough forms. Do not overmix. Lightly grease 15x10-inch jelly roll pan. Press dough into pan. Mix egg white and water until foamy. Brush over dough. Spread walnuts over entire surface. Bake 20-25 minutes, or until lightly golden. Cut into strips immediately and cool on wire rack. Enjoy!