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–+ servings
lemon bar cake with lemon curd and fresh lemon slices.
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5 from 6 votes

Lemon Bar Cake

If you love a classic lemon bar you will love this lemon bar cake! This fresh lemon cake is baked with a shortbread crust on the bottom, filled with tart lemon curd, and a lush cream cheese frosting. It's basically a lemon bar in cake form!

Equipment

Ingredients

Lemon Curd

  • ½ cup lemon juice
  • 4 large egg yolks
  • ⅓ cup granulated sugar
  • 1 tablespoon + 1 tsp lemon zest
  • Pinch fine sea salt
  • 5 ½ tablespoon unsalted butter softened
  • ¾ teaspoon vanilla extract

Shortbread Layer

  • 1 cup + 2 tsp all-purpose flour *see notes for measuring*
  • 9 tablespoon unsalted butter cold and cubed
  • ¼ cup granulated sugar
  • ¾ teaspoon vanilla extract
  • ½ teaspoon fine sea salt

Cake

  • 1 cup granulated sugar
  • 1 tablespoon fresh lemon zest
  • 1 ¼ cups cake flour *see notes for measuring*
  • 2 teaspoon baking powder
  • ¼ teaspoon fine sea salt
  • 3 tablespoon unsalted butter room temperature
  • ½ cup sour cream room temperature
  • 2 tablespoon canola or vegetable oil
  • 1 large egg room temperature
  • ½ cup whole milk room temperature
  • 1 tablespoon fresh lemon juice
  • 1 teaspoon vanilla extract

Cream Cheese Buttercream

  • 1 ½ cups unsalted butter room temperature
  • 2 oz cold cream cheese
  • 1 ½ cups powdered sugar
  • ½ teaspoon vanilla extract
  • 1 teaspoon lemon zest
  • 1 tablespoon heavy cream
US Customary - Metric

Instructions

For the Curd

  • In a small pot, combine the lemon juice, sugar, lemon zest, yolks, and salt.
  • Cook over medium-low heat for 12 minutes, stirring constantly until the curd looks vibrant yellow and is thick enough to coat the back of a spoon.
  • Pour the curd through a fine mesh strainer into a clean bowl. Then stir in the butter and vanilla extract. Cover the top with plastic wrap (so that it touches the curd) and set it in an ice bath to cool.

For the Shortbread

  • Mix the shortbread ingredients in a stand mixing bowl on low speed until crumbly. Press into the prepared 6-inch cake pans. (about 105 g in each one). Bake at 350 for 8 minutes. Set aside to cool while you make the cake batter.

For the Cake

  • In a stand mixing bowl, rub together the sugar and lemon zest. Then add the cake flour, baking powder, and salt and mix to combine.
  • Mix in the cubed butter until it resembles coarse sand.
  • Add the sour cream and oil and mix on low speed for exactly 1 minute. Scrape down the bowl.
  • In a bowl with a spout, whisk together the egg, milk, lemon juice, and vanilla. Slowly stream the liquid into the bowl with the mixer running on low until just combined. Scrape down the sides and bottom of the bowl to ensure everything is well combined.
  • Pour the batter into all three cake pans on top of the shortbread crust, about 225 g in each.
  • Dollop 1 ½ tablespoon of the lemon curd on top of the batter, use a toothpick to swirl it well into the batter.
  • Then bake the cake layers for 23-25 minutes, or until a toothpick inserted into the centers comes out covered in a few moist crumbs.
  • Lem them cool on a wire rack for 15 minutes, then flip them out of the pans. Allow them to cool completely before assembling.

Assembly

  • In a stand mixing bowl, mix the cream cheese on medium speed until smooth, then add the butter and mix to combine.
  • Mix in the powdered sugar on low until combined.
  • Add the heavy cream, vanilla extract, and lemon zest. Increase the speed to medium for 30 seconds until it looks fluffy, but is still thick. Cover and keep the bowl in the fridge until ready to use. If the buttercream looks curdled, it’s likely overmixed. Chill it in the fridge for 30-60 minutes and then mix again and it should come back together.
  • Use a serrated knife to cut a very thin layer off the top of the layers to expose the crumb. Spread a thin layer of buttercream over the top, then pipe a border around the edges (this will keep the curd from oozing out of the sides.)
    Spoon 2-3 tablespoon of the curd in the center, then place the next layer on top. Place the last layer upside down so that the top is completely flat.
  • Use the rest of the buttercream to frost the sides and top.
  • Spoon more lemon curd on the top, garnish with fresh lemon slices or powdered sugar, and enjoy!

Notes

Step-by-step process photos are provided above, in the body of this post.
*Measure your flour properly. This is my #1 baking tip! Do not ever scoop a measuring cup into your flour as this always leads to using too much flour. Instead, use the spoon-level method. This means fluffing the flour first, then spooning it into your measuring cup/spoon. For the BEST results, use a kitchen scale!*