Preheat oven to 180 degrees C. Lightly grease a 20x30cm baking tray.
In a medium bowl cream together the margarine, butter and sugar until smooth. Stir in the egg yolk and vanilla. Combine the flour, salt and 1/2 teaspoon of cinnamon, stir into the creamed mixture.
Press the mixture evenly into the prepared tray. Beat the egg white until frothy and spread it over the top of the dough. Combine the remaining cinnamon and sugar, sprinkle it and the nuts over the top of the dough.
Bake for 15 to 17 minutes in the preheated oven. Cut into diamonds while still warm, then cool completely before removing from the pan.