I needed a cake for a friend’s birthday, and my lemon trees had some beautiful ripe fruit. I imagined a light textured layer cake with bright lemon flavor completed with silky smooth lemon buttercream. This cake was the result: It’s like eating sweet sunshine combined with butter.
This is a longer recipe than usual, as the buttercream is technique driven. I think the results are worth the bit of extra effort required. Enjoy!
Lux Lemon Layer Cake
For the cake: You will be baking a sponge cake, and when the cake is still warm, pouring a lemon syrup onto the layers. Adding a tangy syrup to baked cakes is a great technique to add moisture and flavor while keeping a light and airy texture.
Prepare three 8″ round baking pans by spraying with non-stick baking spray with flour. Use the Hot Milk Sponge Cake recipe, shown below, using the “For Large Cake” version and omitting the 2 tsp. flavoring. Add finely grated zest of two lemons to batter just after adding the hot milk.
Pour the batter into the three prepared 8″ rounds and bake for about 25 minutes.
5 oz. fresh squeezed lemon juice (from 3 – 4 lemons)
2 oz. water
7 oz. (1 cup) sugar
While the cake layers are baking combine the lemon juice, water, and sugar in a sauce pan. Heat until sugar dissolves. After the cake layers come out of the oven, cool in pans for 10 minutes.
Then loosen each layer and return to its pan. Poke several holes on the top of each cake with a fork. Divide the syrup onto the three layers, using a tablespoon to spread evenly onto each layer. After an additional 10 minutes, unmold the cakes and allow to cool to room temp before frosting. May be wrapped in plastic wrap and stored for a day in the fridge before frosting.
For the Lemon Buttercream: This is a classic silky european style swiss meringue buttercream flavored with concentrated fresh lemon juice and pure lemon extract.
juice of three lemons (about 4 oz)
1/2 tsp. pure lemon extract
yellow food color (optional)
5 oz egg whites (from four large eggs)
10 oz (1 1/2 cups) sugar
16 oz unsalted butter, room temp.
Pour the lemon juice into a small saucepan and heat over high heat until boiling. Continue to boil for a minute or two to evaporate 1/2 the water from the juice. Remove the concentrated lemon juice from heat. Cool and set aside.
Add 1 inch water to a medium sized saucepan. Bring to a simmer. Mix the egg whites and the sugar in a clean heatproof mixing bowl. While stirring vigorously with a whisk, heat the egg white/sugar mixture in the heatproof mixing bowl over the simmering water for about 3 minutes. Bring mixture to 140 degrees — or just until all the sugar is dissolved, and the mixture is considerably thinned and slippery feeling on the whisk.
Immediately attach the whisk attachment to your mixer, and beat the hot sugar/eggwhite combo on medium high until very light, barely warm, and smooth. This will take 5 – 8 minutes, depending on room temp and type of mixer/bowl.
Switch to your paddle attachment, and, with the mixer running on low, add the unsalted butter one TB at a time. This can be a tense moment for the new baker — but don’t fear the buttercream! The buttercream will go through a change from marshmallowy to butter cream, and in between it may look a little curdled. Just be patient and mix on low until the buttercream begins to come together. (Great buttercream tutorial here)
When the butter is all incorporated, add the cooled concentrated lemon juice, the pure lemon extract, and the yellow food color to gently color the buttercream a pale yellow.
When the cake layers are cooled, and the buttercrem is ready, fill and frost the cake. Decorate with some lemon slices and voila — Lux Lemon Layer Cake!