Lemon Bar Cake

Moist lemon cake layers are baked on a shortbread crust. Each cake layer is topped with a lemon buttercream frosting, then filled with a tart lemon curd. This cake is fresh, delicious, and tastes JUST like a lemon bar but in cake form!

Course Dessert

Cuisine American

Prep Time 1

Cook Time 1 10

Assembly Time 2

Total Time 4 10

Servings servings

Calories 1174kcal

Author Whitney Wright

Equipment

Ateco cake stand

Ingredients

Shortbread Crust

1 cup unsalted butter cold and cubed
1/2 cup granulated sugar
2 1/2 cups all purpose flour
1/4 teaspoon salt

Lemon Cake

3 cups all purpose flour
1 3/4 cups granulated sugar
1 tablespoon baking powder
1 teaspoon salt
5 large eggs
1/2 cup buttermilk
1 cup sour cream
1 cup vegetable oil
1/2 cup lemon juice freshly squeezed
2 teaspoons vanilla extract
3 tablespoons lemon zest

Lemon Curd

4 large egg yolks
2 large eggs
1 cup granulated sugar
3/4 cup lemon juice freshly squeezed
1 tablespoon lemon zest

Lemon Buttercream

2 1/2 cups unsalted butter slightly cold
7 1/2 cups powdered sugar may need up to 9 cups so have more on hand if needed
2 large lemons zested
2-3 tablespoons lemon juice freshly squeezed
pinch salt
1-3 tablespoons heavy cream

Instructions

Shortbread Crust

Preheat oven to 350º F. Prepare three 8-inch round cake pans by spraying with nonstick spray and lining the bottom with parchment paper.
In a medium-sided mixing bowl combine sugar, flour, and salt. Using forks or a pastry cutter, cut in the cold, cubed butter until the pieces of butter are no larger than the size of a pea. Divide mixture evenly into the prepared cake pans. Press firmly and evenly into the pans using the bottom of a glass or clean hands.
Bake for 11-13 minutes or until edges are golden brown and centers are just starting to get some golden color.
Remove from oven to cool slightly but leave the oven at 350º F to bake the cake layers.

Lemon Cake

In a medium bowl whisk together the flour, sugar, baking powder and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, beat the eggs, buttermilk, sour cream, vegetable oil, lemon juice, vanilla and lemon zest until the mixture is uniform. With the mixer on low, carefully add half of the dry ingredients and mix for about 30 seconds, until it’s mostly combined. Add the rest of the dry ingredients and mix just until no dry streaks remain. Don't over mix.
Divide the batter evenly between three cake pans, pouring it on top of the slightly cooled shortbread crust. Bake for 30-40 minutes, or until a toothpick inserted in the center of the cake layer comes out with a couple moist crumbs stuck to it. (Gentle reminder that cake pans and ovens are all different so be sure to pay close attention to when your cakes are done baking. It may take shorter or longer than the time listed.)
Remove the pans from the oven. When they have cooled enough to handle, flip the cakes out of the pans and onto a cooling rack to cool completely. Using a serrated knife or cake leveler, cut the domed top off of each layer. This will ensure your cake is flat and even when assembled.
If making the cakes ahead of time, wrap each layer in plastic wrap and freeze for up to four weeks. Let the cakes sit at room temperature for one hour before assembling the cake.

Lemon Curd

In a small saucepan over medium heat combine all ingredients. Mix continuously while cooking until the mixture has thickened enough to coat the back of a spoon.
Pour the curd through a fine mesh strainer into a storage container to ensure it is smooth and silky. Place plastic wrap directly onto the top of the curd to prevent a skin from forming as it cools. Cool completely and store in the refrigerator. This curd can be made 3-4 days in advance and stored in the fridge until it’s time to assemble the cake.

Lemon Buttercream

Beat butter, salt, and lemon zest until smooth and light in texture and color. Sift 3 cups of powdered sugar into the butter mixture and mix well, scraping the sides of the bowl as needed.
Add 2 tablespoons of lemon juice and the rest of the powdered sugar and beat for 2-3 minutes.
Add 1 tablespoon of heavy cream and beat for about a minute. Add more heavy cream if the frosting is too thick to spread at room temperature.
The frosting can be made a few days in advance and stored in the refrigerator. A few hours before cake assembly set the frosting out at room temperature. Once the frosting has softened, beat in a stand mixer until smooth and spreadable.

Assembly

Place a cake layer, crust side down, on a cake board or stand that has a small dollop of buttercream on it. This will help keep the cake from sliding around as you assemble it.
Spread a thin layer of lemon buttercream evenly over the top of the cake.
Pipe a rim of buttercream around the top edge of the cake layer to create a dam (make sure the buttercream is slightly cold... see notes section for more details on this), and add 1/2-2/3 cup lemon curd inside the buttercream dam. Be sure to not overfill the cake as it will seep out when you add the next layer and make the cake unstable and difficult to finish icing.
Repeat steps 1 and 2 with the second layer of cake, placing the second cake layer on top of the first layer.
Place the third cake layer on top and crumb coat the entire cake in a thin layer of lemon buttercream. Refrigerate or freeze for a few minutes, until the buttercream is cold and no longer soft.
Add the final layer of frosting around the entire cake. We used extra frosting to create a twisted rope border around the top of the cake and filled the center with extra lemon curd. Add additional decoration as desired.

Notes

Lemon Buttercream: Taste the buttercream as you go! If the lemon buttercream doesn’t taste lemony enough, add more lemon juice, one tablespoon at a time, until you’re happy with how it tastes. Just be sure to not add so much lemon juice that the frosting becomes runny and not able to hold its shape.

Assembly tip: If your buttercream is too warm, decorating the cake will be difficult. The buttercream dam won’t hold the lemon curd in when another layer is placed on top. I’ve found that keeping my buttercream slightly colder than room temperature when I’m decorating a cake makes it the easiest to work with.

We use a third party nutrition calculator to calculate the nutrition facts. It is a estimate and keep in mind not all of the lemon curd or frosting may be used.

Nutrition