Yellow Sheet Cake with Chocolate Frosting

Before you start

Yellow cake earns its name from egg yolks. Three whole eggs plus three extra yolks give this cake its golden color, rich flavor and soft, moist crumb, while butter creamed with sugar provides lift and a classic, slightly sturdy texture that stands up to thick frosting. Baking it in a 23 x 33 cm (9 x 13 in) pan keeps it simple: no leveling, no stacking, frost and serve straight from the pan.

The frosting combines melted chocolate and cocoa for depth, with butter and powdered sugar for body and a splash of cream for a spreadable, glossy finish. Let the chocolate cool until barely warm before adding it, or it will melt the butter and the frosting will turn greasy and loose.

Ingredients

• Cake330 g (2¾ cups) cake flour
• 1 tbsp baking powder
• 1 tsp fine salt
• 225 g (1 cup) unsalted butter — softened
• 350 g (1¾ cups) granulated sugar
• 3 large eggs — room temperature
• 3 large egg yolks — room temperature
• 1 tbsp vanilla extract
• 300 ml (1¼ cups) whole milk — room temperature
• Chocolate frosting115 g (4 oz) semisweet chocolate — chopped
• 170 g (¾ cup) unsalted butter — softened
• 240 g (2 cups) powdered sugar — sifted
• 40 g (½ cup) unsweetened cocoa powder — sifted
• ¼ tsp fine salt
• 60 to 80 ml (4 to 5 tbsp) heavy cream
• 2 tsp vanilla extract

Method

1. Heat the oven to 180°C (350°F). Grease the pan and line the bottom with parchment.
2. Whisk the cake flour, baking powder and salt in a bowl.
3. Beat the butter and sugar on medium-high for 4 minutes, until noticeably paler and fluffy. Scrape the bowl.
4. Add the eggs and yolks one at a time, beating about 20 seconds after each, then beat in the vanilla. The mixture should look smooth and creamy, not curdled.
5. On low speed, add the dry ingredients in three parts alternately with the milk in two parts, mixing only until each addition disappears. Finish folding by hand with a spatula.
6. Spread the batter evenly in the pan. Bake for 30 to 35 minutes, until golden, the center springs back when pressed and a toothpick comes out with a few dry crumbs. Cool completely in the pan on a rack, about 1½ hours.
7. For the frosting, melt the chocolate in 20-second bursts in the microwave, stirring between, until smooth. Let it cool until it feels barely warm on your lip, about 10 minutes.
8. Beat the butter until creamy. Add the powdered sugar, cocoa and salt and beat on low, then add 60 ml cream and the vanilla. Beat in the melted chocolate and whip on medium-high for 2 minutes until fluffy and glossy, adding more cream if it is stiff. Spread over the cooled cake in thick swoops.

Tips for success

• Cake flour gives the classic soft, fine crumb. Spoon it into the cup gently; packed cake flour makes a dry cake.
• Leave the parchment-lined cake in the pan for serving. To turn it out instead, run a knife around the sides once cool and invert onto a board.
• A thin offset spatula dipped in hot water and dried gives a smoother finish on the frosting.

Substitutions

Cake flour

Use 290 g all-purpose flour plus 40 g cornstarch. The crumb is slightly coarser but still tender.

Whole milk

Buttermilk gives a softer, more tender cake; add ½ tsp baking soda and reduce the baking powder to 2 tsp.

Semisweet chocolate

Bittersweet chocolate makes a darker, less sweet frosting. Milk chocolate gives a softer, milder frosting that needs a little less cream.

Variations

Layer cake

Bake in two 23 cm (9 in) round pans for 25 to 30 minutes and double the frosting to fill, crumb coat and cover.

Cupcakes

Fill 24 lined muffin cups two-thirds full and bake for 18 to 21 minutes.

Troubleshooting

Cake sank in the middle

Underbaked, or the oven door opened too early. Bake until the center springs back and avoid opening the oven in the first 20 minutes.

Batter looked curdled

Cold eggs or milk hit the creamed butter. It usually smooths out once the flour goes in, but use room-temperature ingredients next time.

Frosting is grainy or greasy

Grainy means unsifted sugar or cocoa; greasy means the chocolate was too warm. Chill the frosting 10 minutes and re-whip to rescue a loose batch.

Storage

Cover the frosted cake and keep at room temperature for up to 2 days, or refrigerate for up to 5 days and bring slices to room temperature before serving. Unfrosted, wrapped cake freezes for up to 2 months.

Safety notes

The batter has raw egg and flour, so skip licking the beaters. Contains wheat, egg and milk.