Texas Sheet Cake
A thin, fudgy Texas sheet cake made by the boiled-butter method in one bowl and one saucepan, iced with cooked fudge icing while it is still hot from the oven so the topping sets into a glossy shell.
Ingredients
For the Cake
- 1 cup unsalted butter 2 sticks
- 1 cup water
- 5 tbsp unsweetened cocoa powder natural, not Dutch-process
- 2 cups all-purpose flour scooped and leveled
- 2 cups granulated sugar
- 1 tsp baking soda
- 1/2 tsp salt
- 2 large eggs room temperature
- 1/2 cup sour cream full fat, or plain Greek yogurt
For the Fudge Icing
- 1/2 cup unsalted butter 1 stick
- 6 tbsp milk whole milk preferred
- 4 tbsp unsweetened cocoa powder
- 3 1/2 cups powdered sugar sifted if lumpy
- 1 tsp vanilla extract
- 3/4 cup chopped walnuts optional, or pecans
Equipment
- 10x15-inch rimmed jelly roll pan
- Medium saucepan
- Large mixing bowl
- Whisk
Instructions
Make the Batter
- Heat the oven and butter the dish. Set the oven to 350°F (175°C) and butter a 9-by-13-inch baking dish generously, right into the corners. The cake is served from the pan, so there is no parchment.
- Boil the cocoa mixture. Melt the 1 cup of butter in a saucepan over low heat, stir in the water and the 5 tablespoons of cocoa, and bring it to a gentle boil. Take it off the heat and let it cool for a couple of minutes.
- Whisk the dry ingredients. Whisk the flour, granulated sugar, baking soda and salt together in a large bowl, then stir in the eggs and the sour cream. The mixture will look clumpy at this stage, which is correct.
- Combine. Pour the warm cocoa mixture into the bowl in a steady stream, stirring as you go, until the batter is glossy and smooth.
Bake the Cake
- Fill the dish. Pour the batter into the buttered dish.
- Spread it level. Push the batter gently into the corners so it bakes evenly.
- Bake 22 to 26 minutes. A toothpick in the center should come out with a few moist crumbs, not wet batter. The surface should look matte and set and the edges should have pulled slightly from the sides.
Ice While Warm
- Make the icing. With 5 minutes of baking left, bring the 1/2 cup of butter, the milk and the 4 tablespoons of cocoa to a boil in a clean saucepan. Take it off the heat and whisk in the powdered sugar and vanilla until smooth. It should pour rather than spread.
- Pour it over the hot cake. Pour the icing over the cake the moment it comes out of the oven and tilt the pan gently to send it into the corners. Do not push it with a spatula, which drags crumbs into the surface.
Finish and Cool
- Scatter the nuts and cool. Scatter the chopped walnuts over while the icing is still wet so they set into it, then leave the cake alone for at least 30 minutes before cutting.
Notes
Pan size: these quantities are written for a 9-by-13-inch dish, which gives a cake about an inch thick and needs 22 to 26 minutes. In the traditional 15x10 jelly roll pan the cake is half as thick and bakes in 15 to 18 minutes. The icing quantity is the same either way.
Timing: start the icing when the cake has 5 minutes left. It has to go on while the cake is hot so it soaks in and sets into a shell rather than sitting on top as frosting.
Storage: cover loosely with foil at room temperature for up to 3 days, and it is at its best on day two. Refrigerate only in a very warm kitchen, then let a square stand out for 20 minutes before eating.
Freezing: cut into squares once the icing has set, freeze on a tray until firm, then wrap individually for up to 3 months. Thaw wrapped at room temperature for about an hour.
Substitutions: pecans in place of walnuts, buttermilk in place of the sour cream, or a teaspoon of espresso powder in the dry ingredients to deepen the cocoa. Natural cocoa is preferred over Dutch-process, because the baking soda needs the acidity.
Nutrition values are an estimate.
Nutrition
Calories: 320kcal | Carbohydrates: 48g | Protein: 3g | Fat: 14g | Saturated Fat: 8g | Cholesterol: 50mg | Sodium: 185mg | Potassium: 100mg | Fiber: 2g | Sugar: 37g | Vitamin A: 300IU | Calcium: 27mg | Iron: 2.5mg