Easy Sheet Cake with Chocolate Fudge Frosting

Name: Easy Sheet Cake with Chocolate Fudge Frosting
Prep time: 25 min
Cook time: 30 min
Total time: 55 min
Yield: 24 servings
Cuisine: Southern
Ingredients: 1 cup (115 g) pecan halves, toasted, cooled, and coarsely chopped; 2 cups (250 g) all-purpose flour, spooned into the cup and leveled; 2 cups (400 g) granulated sugar; 1 tsp (5 g) baking soda; ½ tsp (3 g) fine salt; 1 cup (2 sticks) (227 g) unsalted butter, cut into tablespoons; ⅓ cup (30 g) unsweetened natural cocoa powder; 1 cup (240 ml) water; ½ cup (120 ml) buttermilk, at room temperature, shaken well; 2 (100 g) large eggs, at room temperature, lightly beaten; 1 tsp (5 ml) pure vanilla extract; ½ cup (1 stick) (113 g) unsalted butter, cut into tablespoons; ⅓ cup (30 g) unsweetened natural cocoa powder; 6 tbsp (90 ml) buttermilk, shaken well; 3½ cups (420 g) powdered sugar, sifted to remove lumps; 1 tsp (5 ml) pure vanilla extract; ¼ tsp (1½ g) fine salt; 1 tbsp (14 g) unsalted butter or nonstick baking spray, softened, for greasing the pan

From the MyKitchenBank Kitchen

A classic Texas-style sheet cake: a tender, buttermilk-enriched chocolate cake baked in a half sheet pan and topped while still warm with a glossy, fudgy pecan frosting that sets into a thin, soft crust. It's made in two saucepans and one bowl, and it feeds a crowd.

Prep: 25 min
Cook: 30 min
Wait: 35 min
Total: 1 hr 30 min
Makes: 1 sheet cake (24 squares)

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Ingredients

24 servings

For the frosting
1 cup (115 g) pecan halves, toasted, cooled, and coarsely chopped
For the cake
2 cups (250 g) all-purpose flour, spooned into the cup and leveled
2 cups (400 g) granulated sugar
1 tsp (5 g) baking soda
½ tsp (3 g) fine salt
1 cup (2 sticks) (227 g) unsalted butter, cut into tablespoons
⅓ cup (30 g) unsweetened natural cocoa powder
1 cup (240 ml) water
½ cup (120 ml) buttermilk, at room temperature, shaken well
2 (100 g) large eggs, at room temperature, lightly beaten
1 tsp (5 ml) pure vanilla extract
For the frosting
½ cup (1 stick) (113 g) unsalted butter, cut into tablespoons
⅓ cup (30 g) unsweetened natural cocoa powder
6 tbsp (90 ml) buttermilk, shaken well
3½ cups (420 g) powdered sugar, sifted to remove lumps
1 tsp (5 ml) pure vanilla extract
¼ tsp (1.5 g) fine salt
1 tbsp (14 g) unsalted butter or nonstick baking spray, softened, for greasing the pan

Equipment (9)

18×13-inch (46×33 cm) rimmed half sheet pan
Large saucepan (4-quart / 4-liter)
Medium saucepan (3-quart / 3-liter)
Large mixing bowl
Whisk and wooden spoon
Fine-mesh sieve
Offset spatula or butter knife
Toothpick or cake tester
Small baking sheet for toasting the pecans

Steps

Before you start

Set out the eggs and buttermilk for 30 minutes so they aren't cold. Cold eggs can firm up the hot butter mixture.
Use a rimmed 18×13-inch (46×33 cm) half sheet pan. A smaller pan will overflow.
Toast the pecans first (step 1) so they're cool enough to stir into the warm frosting.
Make the frosting while the cake bakes. It has to be poured over the cake while both are warm.

1
Toast the pecansOven 350°F / 175°C
- Heat the oven to 350°F (175°C).
- Spread the pecan halves on a small baking sheet and toast for 7 to 8 minutes, until they smell nutty and are a shade darker.
- Tip them onto a cutting board, let them cool for a few minutes, then chop them coarsely.
- Leave the oven on for the cake.
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Ready when: Pecans smell nutty and are lightly browned
Tip: Set a timer. Pecans go from toasted to bitter in under a minute.
2
Prepare the pan
- Grease an 18×13-inch (46×33 cm) rimmed half sheet pan with the softened butter or baking spray.
- Get into the corners and up the sides.
- Place the pan on the counter next to the stove.
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Ready when: Entire inside of the pan is lightly coated, with no dry spots
3
Mix the dry ingredients
- In a large mixing bowl, whisk together the flour, granulated sugar, baking soda, and ½ teaspoon salt for 30 seconds.
- Make sure there are no lumps of baking soda.
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Ready when: Mixture looks uniform in color
4
Boil the cake base
- In a large saucepan, combine the cake butter, ⅓ cup cocoa powder, and water.
- Set it over medium-high heat and stir occasionally until the butter melts and the mixture comes to a full boil, with bubbles breaking across the whole surface, about 4 to 5 minutes.
- Remove it from the heat right away.
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Ready when: Butter fully melted and the mixture is at a rolling boil
Tip: Don't keep it boiling. Extra boiling cooks off water and makes the cake dry.
5
Make the batter
- Pour the hot chocolate mixture over the dry ingredients and whisk until smooth, about 1 minute.
- Whisk in the buttermilk, then the beaten eggs and 1 teaspoon vanilla.
- The batter will be thin and pourable, like heavy cream.
- Scrape it into the prepared pan and tilt the pan so it reaches the corners.
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Ready when: Batter is smooth, glossy, and has no streaks of flour
Tip: Whisk the eggs in after the buttermilk has cooled the batter a bit. This keeps them from scrambling.
6
Bake the cakeOven 350°F / 175°C
- Bake on the middle rack at 350°F (175°C) for 18 to 22 minutes.
- Start the frosting (next step) while it bakes.
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Ready when: A toothpick in the center comes out clean or with a few moist crumbs, and the top springs back when lightly pressed
Tip: Check at 18 minutes. An overbaked sheet cake is dry and the frosting can't rescue it.
7
Cook the frosting base
- About 5 minutes before the cake is done, combine the frosting butter, ⅓ cup cocoa powder, and 6 tablespoons buttermilk in a medium saucepan.
- Cook over medium heat, stirring, until the butter melts and the mixture just begins to bubble at the edges, about 3 to 4 minutes.
- Take it off the heat.
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Ready when: Butter melted, mixture smooth and bubbling at the edges
8
Finish the frosting
- Add the sifted powdered sugar, 1 teaspoon vanilla, and ¼ teaspoon salt to the pan.
- Whisk until completely smooth, then fold in the chopped pecans.
- The frosting should be glossy and pourable, like thick fudge sauce.
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Ready when: No lumps of sugar remain and the frosting flows slowly off the whisk
Tip: If it thickens before you pour it, warm it over low heat for 20 to 30 seconds while stirring.
9
Frost the warm cake
- As soon as the cake comes out of the oven, pour the warm frosting over the hot cake, covering most of the surface.
- Use an offset spatula to spread it gently to the edges and corners.
- The warmth of the cake helps the frosting settle into a thin, smooth layer.
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Ready when: Frosting covers the cake in an even, glossy layer all the way to the edges
Tip: Work quickly. The frosting is easiest to spread in the first 2 minutes.
10
Cool and set
- Let the cake cool in the pan on a wire rack for at least 30 minutes, until the frosting is no longer shiny-wet and a light skin has formed.
- Cut into 24 squares (4 rows by 6 rows) and serve warm or at room temperature.
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Ready when: Frosting is matte with a light skin and doesn't stick to a finger touched lightly to the surface
Tip: Wipe the knife between cuts for clean edges.

Good to know

Tips

Pour the frosting over the cake while both are warm. The frosting melts slightly into the surface, which makes the signature fudgy layer.
Sift the powdered sugar. Lumps are hard to whisk out of the frosting once the cocoa mixture begins to cool.
The batter is thin, which is normal. Whisk just until smooth.
Don't swap in a smaller pan. A standard 18×13-inch half sheet pan gives the right thickness and bake time.

Make ahead

The cake can be baked, frosted, and cooled up to 1 day ahead. Cover the pan tightly once the cake has cooled completely, and keep it at room temperature.

Storage & reheating

Room temperature: covered tightly, up to 3 days. Refrigerator: up to 5 days, but let squares sit at room temperature for 20 minutes before serving. Freezer: wrap individual squares or the whole cake tightly in plastic wrap and then foil, and freeze for up to 3 months. Thaw overnight in the refrigerator, or at room temperature for about 2 hours. Warm individual squares in the microwave for 10 to 15 seconds if you like.

Substitutions

buttermilk → 1 tbsp lemon juice or white vinegar in a measuring cup, filled to the line with whole milk. Let it stand for 5 minutes until slightly thickened. Use the same method for the frosting buttermilk.
pecan halves → Toasted walnuts, or leave them out. Walnuts are a bit more bitter. Without nuts the frosting is smoother and the cake is nut-free.
unsweetened natural cocoa powder → Dutch-process cocoa powder. The cake will be slightly darker and milder. It still works because the buttermilk supplies enough acid for the baking soda.
pure vanilla extract → ½ tsp ground cinnamon. Gives a Mexican-chocolate flavor. Whisk it into the dry ingredients.