Large Texas Sheet Cake for a Crowd

Large Texas sheet cake is a thin, tender chocolate cake baked in a large rimmed sheet pan and covered with warm cocoa frosting. This crowd-friendly version uses a 13-by-18-inch half-sheet pan, pantry ingredients, and a pourable icing that sets into a soft, fudgy layer.

Ingredients

2 cups (250 g) all-purpose flour, spooned into the measuring cup and leveled
2 cups (400 g) granulated sugar
1 teaspoon baking soda (5 g)
½ teaspoon fine salt (3 g)
1 cup (240 ml) water
1 cup (226 g) unsalted butter, cut into pieces
⅓ cup (28 g) unsweetened natural cocoa powder
½ cup (120 ml) buttermilk, at room temperature
2 large eggs (about 100 g without shells), at room temperature
1 teaspoon vanilla extract (5 ml)
For the frosting: ½ cup (113 g) unsalted butter
⅓ cup (28 g) unsweetened natural cocoa powder
6 tablespoons (90 ml) milk
3½ cups (420 g) powdered sugar, sifted if lumpy
1 teaspoon vanilla extract (5 ml)
½ cup (60 g) chopped pecans, optional

Instructions

Heat the oven to 350°F (175°C). Grease a 13-by-18-inch rimmed half-sheet pan, then line the bottom with parchment if you want easier lifting and slicing. A rimmed pan is essential because the batter is thin and the frosting is poured on while warm; do not use a flat cookie sheet. Measure the flour by spooning it into the cup and leveling it, rather than packing it down.
Whisk the flour, sugar, baking soda, and salt together in a large heatproof mixing bowl. In a medium saucepan, combine the water, 1 cup (226 g) butter, and ⅓ cup (28 g) cocoa. Bring to a gentle boil over medium heat, stirring until the butter melts and the cocoa mixture is smooth. Pour it over the dry ingredients and stir just until no dry streaks remain.
In a separate bowl, whisk the buttermilk, eggs, and 1 teaspoon vanilla until blended. Slowly stir this mixture into the chocolate batter until evenly combined; avoid beating it for a long time, which can make the cake less tender. Pour the batter into the prepared pan and spread it into the corners. Bake for 18–22 minutes, rotating the pan once if your oven browns unevenly. The cake is done when the center springs back lightly and a toothpick comes out with a few moist crumbs, not wet batter. Do not wait for the cake to become dry.
While the cake bakes, make the frosting. Put ½ cup (113 g) butter, ⅓ cup (28 g) cocoa, and 6 tablespoons (90 ml) milk in a saucepan. Heat over medium-low, stirring until the butter melts and the mixture is smooth; do not let it boil hard. Take the pan off the heat. Whisk in the powdered sugar a cup at a time, then stir in 1 teaspoon vanilla and the pecans, if using. If it seems too thick to pour, mix in milk 1 teaspoon (5 ml) at a time; if too thin, add a little more powdered sugar.
Set the pan on a stable, heatproof surface as soon as the cake comes out of the oven. Pour the warm frosting over the hot cake and gently spread it to the edges with an offset spatula or the back of a spoon. Let it stand in the pan until the icing is set enough to slice, usually 30–45 minutes. For especially neat pieces, cool it fully before cutting into 24 squares.

Tips

Use the specified 13-by-18-inch rimmed pan for the intended thin cake and baking time. A smaller pan makes the batter deeper and changes the bake; don’t fill a pan past its safe capacity.
Buttermilk helps keep the crumb tender. If you do not have it, stir 1½ teaspoons lemon juice or white vinegar into ½ cup (120 ml) milk, wait 5 minutes, and use it in place of the buttermilk. The flavor and texture will be slightly less rich.
Have the frosting ingredients measured before the cake comes out. Pouring warm frosting over a hot cake helps it spread evenly; waiting until the cake is cool can make the icing difficult to distribute.
For easier serving, wipe the knife between cuts and let the cake cool until the frosting is set. Pecans are optional; omit them for a nut-free cake, and check ingredient labels if serving someone with an allergy.

Serving Suggestions

Serve the cake in small squares at room temperature, where the chocolate flavor and soft icing are easy to enjoy. It pairs well with unsweetened coffee, cold milk, or fresh berries. For a plated dessert, add a spoonful of lightly sweetened whipped cream or a small scoop of vanilla ice cream just before serving. Since this is a rich, thin cake with a generous frosting layer, modest squares are usually plenty for a dessert table.

Variations

For a classic nut-free finish, leave out the pecans. You can instead sprinkle the warm icing with a little flaky salt, or add ½ cup (85 g) mini chocolate chips after the frosting has been spread. For a deeper cocoa flavor, use Dutch-process cocoa in both cake and frosting; the cake’s acidity and rise can vary slightly, so natural cocoa is the straightforward choice for this baking-soda recipe. A teaspoon of instant espresso powder dissolved in the cake’s hot water adds background depth without making the cake taste strongly of coffee.

To make a slightly tangier frosting, replace up to 2 tablespoons (30 ml) of the milk with buttermilk, then add the remaining milk gradually until the icing pours easily. For a dairy-free version, use plant-based butter sticks and an unsweetened plant milk. Texture and flavor may differ by product, so choose a baking-style butter substitute rather than a soft tub spread.

Storage and Reheating

Once cooled, cover the pan or transfer cut pieces to an airtight container. Refrigerate within 2 hours; the cake keeps for 3–4 days refrigerated. Let slices sit at room temperature for about 20–30 minutes before serving for a softer crumb and icing. For longer storage, freeze individual pieces, wrapped tightly and placed in a freezer-safe container, for up to 2 months; thaw overnight in the refrigerator or at room temperature. This cake is best served at room temperature, so reheating is not necessary. If you prefer a warm slice, microwave one piece briefly, about 8–10 seconds, and avoid overheating, which can melt the frosting.

Frequently Asked Questions

Can I make Texas sheet cake in a 9-by-13-inch pan?
Not with the same quantities and baking time: this recipe is scaled for a 13-by-18-inch half-sheet pan. A 9-by-13-inch pan holds less surface area, so the batter would be much deeper and could overflow or bake unevenly. Use a recipe specifically designed for that pan size.

Why is the frosting poured over the cake while it is hot?
The warm cake helps the pourable frosting spread into a smooth layer and adhere to the surface. The icing firms as it cools. Work carefully with the hot pan and saucepan, and place the cake on a steady heatproof surface before frosting.

Can I make the cake ahead?
Yes. Bake and frost it the day before, allow the icing to set, then cover and refrigerate. Bring it toward room temperature before serving. You can also bake the cake a day ahead and add freshly made frosting later, but the traditional warm-on-warm method gives the most even coating.

How do I know when the cake is baked?
Start checking at 18 minutes. The center should spring back lightly when touched, and a toothpick inserted in the middle should come out with a few moist crumbs rather than liquid batter. Ovens and pans vary, so use the visual checks along with the time.

Can I leave out the nuts?
Yes. Pecans are optional and can be omitted without changing the frosting method. If you are serving guests with allergies, keep nuts away from the work area and check labels on all packaged ingredients to avoid cross-contact.

Can I use salted butter?
Yes. Use the same quantity and reduce the added fine salt in the cake to a small pinch or omit it. Salt levels vary by brand, so taste the frosting before adding any extra salt.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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