Mexican Chocolate Cake

A good friend of mine, who is a fantastic cook, once told me that putting cinnamon in a chocolate cake is common in Mexico.  I didn't know that, but grew up eating this chocolate sheet cake.  I've started calling it Mexican Chocolate cake, just to differentiate it from other chocolate cakes I make.  This one might be my favorite.

Mexican Chocolate Cake
2 c. sugar
2 c. flour
100 g. butter
1/2 c. dalda or vanaspati
4 T. cocoa
1 c. cold water
1/2 c. milk
1 t. vinegar
1/4 t. salt
1 t. soda
1 t. cinnamon
1 t. vanilla
 2 eggs

Icing
1/3 c. milk
4 T. cocoa
1 t. vanilla
100 g. butter
3 1/2- 4 c. powdered sugar

Combine the milk and vinegar and let sit.  Combine sugar and flour in a large bowl.  Bring butter, shortening, cocoa and water to a boil in a saucepan.  Pour boiling mixture over flour and sugar.  Beat well.  Add the milk and vinegar combination, salt, soda, cinnamon, vanilla and eggs.  Grease a 9x13 cake pan and pour the batter in.  Bake for 20 minutes at 375/190.

To make frosting, put milk, cocoa and butter in saucepan.  Bring to a boil.  Add vanilla and sugar.  Beat.  Pour it over the hot cake.  The icing will set very quickly.