This is a very moist chocolate sheet cake. How it got the name Texas Sheet Cake I haven't a clue. That was the name it had when I got the recipe, and I don't know it by any other name. I like this cake because it is made in a jelly roll pan, and anything made in a sheet pan or jelly roll pan you can get a lot of servings from it. You can put nuts on the top, the recipe says to mix them in the icing, but I just put them on top, usually on only half the cake, since some people don't like or can't eat nuts. Either way it's a good chocolate cake.
Boil first 3 ingredients together, (water,margarine,cocoa), for 2 minutes. Stirring mixture to be sure it doesn't lump together.
In mixing bowl add remaining cake ingredients, start mixer on low and slowly pour hot water/margarine/cocoa mixture. Mix well scraping bowl to be sure it has mixed well.
Pour cake mixture into a jelly roll pan, or a pan that is 15 1/2 inches by 10 1/2 inches, or a pan that is 17 inches by 11 inches. Bake cake in a 325 oven for 20 to 30 minutes depending on the size of your pan.
Icing: Boil first 3 ingredients together, (milk,cocoa,margarine), boil for 1 minute. Stirring mixture to be sure it doesn't lump together.
Add confectioners sugar to mixing bowl, with the vanilla, turn mixture on low, and slowly pour in hot milk,cocoa,margarine mixture. Continue beating icing until mixture is blended together well. You can add the nuts to the icing at this point if you like too. Icing will be thin.
Remove cake from oven and let cool 5 minutes before pouring the icing over the cake. I put my cake on a cake rack over a sheet of paper, icing sometimes runs over the sides. I sprinkle nuts on 1/2 the cake.