In a mixing bowl, beat the butter for 30 seconds. Add the sugar and beat until fluffy. Add the egg yolk; beat well.
Stir together the flour, cinnamon, and baking soda. Add to the butter mixture, beating until just combined.
Place the dough in the center of a 15x10x1-inch baking pan. Spread the dough evenly in the shallow pan.
Brush the top of the dough with the egg white and sprinkle with almonds, pressing almonds into the dough.
Bake the cookies in a 350 degree F oven for 15 to 18 minutes or until the dough is golden brown. Remove the pan from the oven. Let stand for 5 minutes. Immediately cut into squares. Remove and cool on wire rack.
Mix together the Powdered Sugar Icing, if you like. Drizzle over the bars. Makes 36 bars.
Mix together powdered sugar, milk, and vanilla. Stir in more milk, a teaspoon at a time, until mixture is a drizzling consistency.