A recipe for Texas sheet cake is featured in Southern Living, which uses sugar, flour, eggs, butter, shortening and various sweetening ingredients. While the cake is baking, you can make a homemade icing to top it.
To make a classic Texas sheet cake from scratch, whisk together 2 cups of sugar and 2 cups of all-purpose flour in one bowl, and combine 1/2 cup of butter, 1/2 cup of shortening, 1/4 cup of unsweetened cocoa and 1 cup of water in a saucepan. Bring the mixture to a boil, stirring well, and mix it into the flour mixture. Once the batter starts to cool, add 1/2 cup of buttermilk, 2 lightly beaten eggs, 1 teaspoon of baking soda and 1 teaspoon of vanilla. Spoon the batter into a rimmed baking sheet, and cook at 400 degrees Fahrenheit for 20 minutes.
As the cake bakes, pour 1/2 cup of butter, 1/4 cup of unsweetened cocoa and 1/3 cup of milk in a saucepan, and heat the mixture until the butter melts. Once it starts to boil, add 1 16-ounce package of powdered sugar, 1 teaspoon of vanilla and 1 cup of chopped pecans. Beat the frosting until it has a smooth texture, and frost the cooled cake.