To make a Texas sheet cake, boil water, cocoa and butter in a big saucepan, and set aside. Add a mixture of flour, salt, sugar and baking soda to the cocoa mixture. Whisk in the sour cream, transfer to a greased baking pan, and bake for 20 to 25 minutes.
Taste of Home's Texas Sheet Cake does not use eggs and calls for 1 cup cubed butter, 1 cup water, 1/4 cup baking cocoa, 2 cups all-purpose flour and 2 cups sugar. It also requires 1/2 cup sour cream, 1/2 teaspoon salt and 1 teaspoon baking soda. Use a 15-by-10-by-1-inch baking pan, and bake at 350 degrees Fahrenheit. To check if the cake is ready, insert a toothpick near the center, and see if bits of the cake do not stick.
To create the icing, melt 1/2 cup cubed butter in a small saucepan, and pour in 1/4 cup plus 2 tablespoons milk and 3 tablespoons baking cocoa. Set aside once the liquid boils. Stir 3 3/4 cups confectioners' sugar and 1 teaspoon vanilla extract until smooth. Distribute the icing evenly over the freshly baked cake, and let the cake cool on a wire rack. This recipe takes 20 minutes to prepare and 20 minutes to bake.