Preheat oven to 375°F and coat a 10x15" jelly roll pan with non-stick cooking spray.
Heat the butter and water in a medium saucepan over medium-high heat until the butter is melted and the mixture starts to simmer, then remove pot from heat.
In a large bowl, whisk together the flour, sugar, baking soda and salt. Pour the butter mixture into the bowl of dry ingredients. Stir just until combined.
Mix in the eggs, sour cream, and vanilla extract.
Pour the batter into the prepared jelly roll pan and bake for 18-22 minutes, or until a toothpick inserted in the center comes out clean. Cool the cake in the pan for 5-10 minutes while you prepare the frosting.
Frosting Directions
Melt the butter and milk together in a medium saucepan over medium heat. Increase the temperature to medium-high, until the mixture begins to simmer.
In a large mixing bowl, combine the powdered sugar, vanilla extract, and the melted butter mixture. Whisk together until smooth.
Pour the frosting on top of the cake, while it is still warm, and spread out evenly.
Cool the cake and allow frosting to set completely before slicing and serving.
Notes
Nutrition information is an estimate only.Prep Tips:
Cake Pan – This cake can be made in a traditional jelly roll pan (10 x 15 inches, with raised sides) or with a 9x13 inch cake pan.
Nuts – A traditional chocolate Texas sheet cake is often topped with pecan halves or chopped pecans. White Texas Sheet Cake is almond flavored, so we topped it with sliced almonds.
Variations - For a gluten free cake, use 1:1 gluten free all purpose flour. For a lactose free cake, use a creamy plant based milk such as cashew milk or oat milk.