Mix the sugar, cocoa powder, flour, cinnamon, baking powder, baking soda and salt in a bowl and set aside. Put milk, egg yolk, margarine and vanilla extract in another bowl and mix as well. Beat the egg whites until stiff.
Add the liquid mix to the first mix and mix well. Stir in the egg whites. Now add the chopped chocolate and walnuts and let rest for 5 minutes.
Then bake in portions in the preheated waffle iron.