This vanilla sheet cake is a soft buttermilk cake baked in a 9×13 pan and spread with a thick vanilla buttercream. The batter is 2 ½ cups flour, 1 ¾ cups sugar, 3 eggs, ¾ cup butter and 1 cup buttermilk, it bakes at 350°F for 30 to 35 minutes, and it cuts into 16 slices.
The one step not to rush is creaming the butter and sugar. Three to four minutes of beating is what makes the crumb light enough to frost straight in the pan.
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- Pan: one 9×13 inch pan, greased and lined with parchment on the bottom. This is the size bakeries call a quarter sheet. Metal browns more evenly than glass.
- Oven: 350°F (175°C), 30 to 35 minutes
- Time: 20 minutes prep, 35 minutes baking, about 1 hour cooling before frosting
- Servings: 16 slices cut 4 by 4 (about 3 by 2 ¼ inches each), or 24 party squares cut 6 by 4
- Lift: 2 ½ teaspoons baking powder plus ½ teaspoon baking soda, which reacts with the buttermilk
- Frosting: 1 cup butter and 3 cups powdered sugar, enough for a generous layer on top
Flour, Butter, Eggs and Buttermilk
All purpose flour is the right choice here. Cake flour gives a silkier bite, but the slices are more fragile and can tear when you spread frosting over them in the pan. Weigh it if you can: 315 grams. Scooping straight from the bag packs in extra flour and gives you a dry, domed cake.
Granulated sugar does more than sweeten. It holds on to moisture, which is why the cake is still soft on day three. Butter gives the flavor, and three eggs give the structure that lets you serve squares straight from the pan without them crumbling.
Buttermilk is the quiet one. Its acid softens the gluten so the crumb stays tender as it cools, and it feeds the baking soda for a little extra rise. No buttermilk? Stir 1 tablespoon of lemon juice or white vinegar into 1 cup of milk and let it stand 10 minutes. It works, though the crumb is a touch less fine. The Texas sheet cake uses sour cream for the same tenderizing job.
Take the butter, eggs and buttermilk out about an hour ahead. Cold eggs and buttermilk make creamed butter seize into little lumps, and the batter never quite smooths out.
Creaming Butter and Sugar for a Light Crumb
Beat the softened butter and sugar on medium speed for 3 to 4 minutes. It should turn from yellow to almost ivory and look fluffy, like thick whipped cream. Rub a little between two fingers. If it still feels gritty, keep going.
This is where most of the lift comes from. Sugar crystals cut tiny air pockets into the butter, and the baking powder only makes those pockets bigger in the oven. A short creaming time gives a flat, heavy sheet cake no matter how fresh your leavening is.
Add the eggs one at a time, then the 2 teaspoons of vanilla. The mixture may look slightly curdled after the last egg. That is normal, and it comes back together once the flour goes in.
Three Dry Additions, Two Buttermilk
Whisk the flour, baking powder, baking soda and salt in a separate bowl first so the leavening is spread evenly. Then add it to the butter in three parts, with the buttermilk in two parts between them. Start and end with the dry mix.
Mix on low and stop as soon as each addition disappears. The finished batter is thick, smooth and pale, and it falls from the spatula in slow ribbons. Beating it longer at this point develops gluten and gives you a tough cake with tunnels.
How Long to Bake a 9×13 Sheet Cake
Spread the batter into the lined pan. It moves slowly, like thick yogurt, so push it into the corners with an offset spatula and smooth the top. Skip hard tapping on the counter, which knocks out the air you just beat in.
Bake at 350°F for 30 to 35 minutes. Start checking at 30. The cake is done when the top springs back under a light press, a toothpick from the center comes out clean or with a few moist crumbs, and the edges are just pulling away from the pan. If you hold your ear close and it is still sizzling loudly, give it a few more minutes.
Let it cool completely in the pan on a wire rack, about an hour. Frosting a warm cake melts the butter in the buttercream and it slides right off.
The Buttercream That Goes With It
The frosting is a simple American buttercream. Beat 1 cup of softened butter for 2 minutes until smooth, then add 3 cups of sifted powdered sugar one cup at a time, scraping the bowl. Add 1 tablespoon vanilla, a pinch of salt and 2 tablespoons of heavy cream or milk, then beat on medium high for 3 to 4 minutes.
It is ready when it looks pale and fluffy and holds soft swirls. Too stiff to spread without tearing the cake? Beat in milk a teaspoon at a time. Too soft on a warm day? Chill the bowl for 10 minutes and beat again. Spread it with an offset spatula or the back of a spoon and make swirls on top.
Want a different finish? This cake also takes cream cheese frosting, a lighter whipped cream frosting if you keep it chilled, or my vanilla buttercream frosting for piping borders.
Scaling Up to a 12×18 or Half Sheet Pan
A 13×18 half sheet pan has exactly twice the area of a 9×13, so make a double batch of batter and a double batch of frosting. A 12×18 pan is slightly smaller, and a double batch fills it a little deeper.
Use a cake pan that is 2 inches deep. A regular 1 inch rimmed baking sheet is too shallow for a double batch and will overflow. The bigger pan also takes longer because the heat needs more time to reach the middle. Check at 35 minutes and go by the spring back and the toothpick, not the clock. A doubled cake cut into 2 inch squares serves a big crowd.
Mix a double batch only if your mixer bowl holds it comfortably. If it is a squeeze, make two single batches back to back and pour them into the same pan.
Vanilla Sheet Cake vs White Sheet Cake
The difference is the eggs. This vanilla sheet cake uses 3 whole eggs, so the yolks give it a pale yellow crumb and a richer, buttery taste. A white cake uses only egg whites, which makes a snow white, slightly drier and springier crumb that suits wedding colors.
If color matters more than flavor, a dedicated white cake recipe is the better route, because swapping whites for whole eggs here changes the liquid balance. For a richer vanilla layer cake in round pans, try my simple moist vanilla cake.
Why a Sheet Cake Sinks, Dries Out or Sticks
- Sunken middle: usually pulled from the oven too soon, or the door was opened in the first 20 minutes. Old or heaped baking powder can also make it rise fast and fall. Bake until the center springs back.
- Tough crumb with tunnels: the batter was beaten after the flour went in. Mix each addition on low only until it disappears.
- Dry edges: overbaked, or the oven runs hot. An oven thermometer often shows 15 to 25 degrees of difference.
- Frosting slides off: the cake was still warm. Wait the full hour.
- Stuck to the pan: grease the pan and line the bottom with parchment, even if you serve it from the pan.
Sprinkles, Almond and Other Twists
Fold ½ cup of sprinkles into the finished batter and it turns into a simple birthday cake for a party. One teaspoon of almond extract added with the vanilla deepens the flavor without taking over.
Top the frosted cake with berries, or skip the buttercream and serve it with fruit and whipped cream in summer. Plain squares are good with morning coffee, and leftover cake cubes make a fine base for a Christmas trifle. For a chocolate version of the same idea, there is my chocolate sheet cake, and the peanut butter sheet cake has a batter just as sturdy under toppings.
Keeping Leftover Squares Soft
Covered at room temperature, the frosted cake keeps for up to 3 days. In the fridge it lasts 5 days. Let chilled slices sit out for 20 to 30 minutes so the buttercream softens and the crumb loses its chill.
You can bake and frost it a day ahead and keep it covered in the fridge. To freeze, wrap slices individually and thaw them overnight in the fridge. The crumb stays soft, though the frosting may look a little dull until it comes to room temperature.
Vanilla Sheet Cake
This vanilla sheet cake is a soft buttermilk cake baked in a 9x13 pan and topped with a fluffy vanilla buttercream, made with all purpose flour, butter, sugar, three eggs and buttermilk. It bakes at 350°F for 30 to 35 minutes and cuts into 16 slices, with a tender, moist crumb that is sturdy enough to frost and serve straight from the pan. Creaming the butter and sugar for 3 to 4 minutes gives the lift, and buttermilk keeps the cake soft for days. Use this 9x13 vanilla cake recipe for birthday sheet cakes, potlucks, school parties, or cut into squares for a crowd; double it for a 12x18 or half sheet pan. Stir in sprinkles or almond extract for a twist. Keeps 3 days covered or 5 days in the fridge.
Ingredients
- FOR THE VANILLA SHEET CAKE:
- 2 ½ cups (315g) all-purpose flour
- 2 ½ teaspoons baking powder
- ½ teaspoon baking soda
- ½ teaspoon fine salt
- ¾ cup (170g) unsalted butter, softened
- 1 ¾ cups (350g) granulated sugar
- 3 large eggs, room temperature
- 2 teaspoons pure vanilla extract
- 1 cup (240ml) buttermilk, room temperature
- FOR THE CREAMY VANILLA FROSTING:
- 1 cup (226g) unsalted butter, softened
- 3 cups (360g) powdered sugar, sifted
- 2 tablespoons heavy cream or milk
- 1 tablespoon pure vanilla extract
- Pinch of salt
Instructions
- PREPARE THE PAN: Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking pan and line the bottom with parchment paper for easy removal after baking.
- MIX DRY INGREDIENTS: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until evenly combined. Set aside.
- CREAM BUTTER AND SUGAR: In a large mixing bowl, beat the softened butter and granulated sugar together on medium speed for 3 to 4 minutes until the mixture is light and fluffy.
- ADD EGGS AND VANILLA: Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract until fully incorporated.
- ALTERNATE WET AND DRY: Add the dry ingredients in three additions, alternating with the buttermilk. Begin and end with the dry ingredients. Mix each addition just until combined to avoid overmixing.
- TRANSFER TO PAN: Pour the batter into the prepared baking pan. Use a spatula to smooth the top into an even layer.
- BAKE: Bake the cake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs attached.
- COOL COMPLETELY: Allow the cake to cool fully in the pan on a wire rack before adding the frosting. Do not frost while warm.
- MAKE THE FROSTING: In a large bowl, beat the butter on medium speed for 2 minutes until smooth and creamy. Gradually add the sifted powdered sugar, one cup at a time, beating well and scraping the bowl as needed.
- ADD VANILLA AND CREAM: Add the vanilla extract, a pinch of salt, and the heavy cream or milk. Beat on medium-high speed for 3 to 4 minutes until the frosting becomes light, fluffy, and spreadable.
- FROST THE CAKE: Use an offset spatula or the back of a spoon to spread the frosting evenly over the cooled cake. Serve in slices and store leftovers covered at room temperature or in the refrigerator.
Notes
Weigh the flour (315 g) or spoon and level it; packed flour makes a dry, domed cake.
Have the butter, eggs and buttermilk at room temperature so the batter stays smooth.
Cream the butter and sugar for the full 3 to 4 minutes until pale and no longer gritty.
Do not open the oven in the first 20 minutes, and bake until the center springs back; an underbaked center sinks.
Cool the cake completely, about 1 hour, before frosting.
No buttermilk: stir 1 tablespoon lemon juice or white vinegar into 1 cup milk and let it stand 10 minutes.
For a 13x18 half sheet pan, double the batter and frosting, use a 2 inch deep pan and start checking at 35 minutes.
The frosted cake can be made a day ahead and kept covered in the refrigerator. Store leftovers covered for 3 days at room temperature or 5 days in the fridge; freeze wrapped slices and thaw overnight in the fridge.
For a stronger vanilla flavor, use vanilla bean paste in place of extract.
