1tsp coarse Kosher salt(if using table salt, use half the amount)
3(165g)large eggs
2(70g)large egg whites only(save the yolks for another use)
½cup (120g)sour cream
1cup (224g)vegetable oil
1tsp (4g)vanilla extract
Buttercream
2cups (452g)unsalted butter,softened to room temperature
4cups (560g)powdered sugar
1tbsp (9g)meringue powder(optional)
⅛tsp coarse Kosher salt(if using table salt, use half the amount)
2tsp (8g)lemon extract
1tsp (4g)vanilla extract
zest of 1 small lemon
2-4tbsp (33-66ml)milk or cream,if needed
Instructions
Cake
Preheat the oven to 350 F. Line three 8-inch cake pans with parchment paper in the bottoms of the pans, and spray the paper with non-stick spray. The baked cakes are sticky, and you should not skip this step of lining your pans with parchment paper.
In a measuring cup, stir together the lemon juice and milk; set aside for about 15 minutes to let the milk curdle.
Measure the sugar into a large bowl, and zest the lemons over the sugar. Use your fingers to rub the lemon zest into the sugar to really infuse the lemon flavor.
Set a fine mesh strainer over the sugar, and sift in the flour, baking soda, baking powder and salt, then whisk together the dry ingredients with the lemon sugar.
In a separate bowl, whisk together the lemon juice/milk mixture, eggs, egg whites, sour cream, oil and vanilla until smooth. Add the wet ingredients to the dry and whisk by hand until smooth, about 30 seconds.
Divide the batter between the pans. Bake for 25-27 minutes, until a cake tester in the center of the cakes comes out clean and the tops spring back when lightly touched. Set the pans on a wire rack, cover with a clean kitchen towel, and cool completely.
Buttercream
In the bowl of your stand mixer fitted with the whisk attachment, beat the butter for one minute until smooth. Scrape the bowl down. With the mixer on low, add the powdered sugar, meringue powder and salt, mixing to combine. Add the lemon extract, vanilla extract and lemon zest.
Beat on medium high for about 5 minutes, scraping the bowl down occasionally, until very light and fluffy. Add the milk as needed for desired consistency.
Remove the cooled cakes from the pans. Fill and frost the cooled cakes with the buttercream.
Notes
I’ve only made this recipe using cake flour, and it produces a very light, fluffy cake. All-purpose flour will not give you quite the same result, but should still be fine. Be sure to sift the flour to get out any lumps.
It’s a good idea to set out your dairy products (eggs, milk, sour cream) an hour or two before you mix your batter, to let them come to room temperature. Large eggs can vary in size, but they should average about 1/4 cup each in volume; three large eggs plus two whites should fill one cup. If your eggs are on the small side, add another to get a full cup.
Lemons also can vary in size, as well as how much juice they contain. You might need 4 small lemons to get 1/2 cup of juice for the cake batter.
Although there is plenty of fresh lemon juice and zest in the cake, for the buttercream I decided to only use lemon extract. Adding lemon juice to buttercream runs the risk of curdling the butter; I have had this happen sometimes, and other times not, but based on experience, I think it’s best not to add the acidic juice and risk ruining a whole bowl of buttercream.
These cakes are extremely light and fluffy, and will stick to your cake pans if you don’t line them with parchment paper. Take this extra step to ensure easy release.
For a Lemon Poppyseed Cake, add two tablespoons poppy seeds to the dry ingredients.
To add even more tart lemony goodness, you can spread a bit of lemon curd between each cake layer.
Be sure to review my Baking FAQs for my other tips on cake baking.
This cake will stay moist for days if stored in an airtight container or cake carrier.