• This Texas Sheet Cake comes together quickly, so it helps to have everything measured and ready. The best part? You’ll pour the warm chocolate frosting over the cake while it’s still warm—this is what gives that signature fudgy finish.

Prep your pan and oven

• Preheat your oven to 350°F (175°C).
• Grease a rimmed baking sheet/jelly roll pan (about 18x13 inches) and line it with parchment if you want extra-easy lifting and clean slices.
• Quick tip: A rimmed pan matters here—this chocolate sheet cake batter is thin and needs edges.

Mix the dry ingredients

• In a large bowl, whisk together:
• flour
• sugar
• cocoa powder
• baking soda
• salt
• Whisking now prevents cocoa pockets later and keeps the crumb even.

Warm the cocoa-butter mixture

• In a saucepan over medium heat, melt butter with the water.
• Once melted, whisk in the cocoa powder until smooth.
• Bring it just to a gentle simmer, then remove from heat.
• You’re not trying to “boil” it hard—just warm and glossy so it blends easily.

Combine the batter (smooth, not overmixed)

• Pour the warm cocoa mixture into the bowl of dry ingredients.
• Stir until the batter looks evenly chocolatey.
• Add the eggs, buttermilk, and vanilla, then mix until smooth.
• Friend-to-friend guidance: Mix only until everything comes together. Overmixing can make a cake bake up tougher instead of tender and ultra-moist.

Bake

• Pour the batter into your prepared pan and spread it into an even layer.
• Bake for 18–22 minutes, or until:
• the center springs back lightly when touched, and
• a toothpick comes out with a few moist crumbs (not wet batter).
• Don’t chase “bone dry.” Pulling it at the right moment is the secret to a truly moist chocolate sheet cake.

Make the warm poured frosting

• While the cake bakes (or as it comes out), make the frosting:
• In a saucepan, melt butter with milk.
• Whisk in the cocoa powder until smooth.
• Remove from heat and stir in vanilla.
• Gradually whisk in powdered sugar until glossy and pourable.
• Fold in pecans if using.
• Consistency check: It should flow like thick chocolate sauce. If it feels too thick, add 1–2 teaspoons milk. If too thin, add a spoonful of powdered sugar.

Frost while warm, then let it set

• As soon as the cake comes out of the oven, pour the frosting over the warm surface.
• Gently spread it to the edges with an offset spatula or the back of a spoon.
• Let it rest 15–30 minutes so the frosting can settle into that soft, fudgy layer—then slice and serve.
• That’s it—simple steps, one pan, and the classic Texas Sheet Cake payoff every time.