Lemon Cake & Icing

3 cups cake flour
1 1/2 teaspoons baking powder
1 teaspoon salt
1/2 teaspoon baking soda
1 cup butter, softened
2 1/2 cups sugar
5 eggs
1 teaspoon vanilla extract
1/4 cup plus 2 tablespoons lemon juice
3/4 cup buttermilk

1. Make the batter: Preheat oven to 350 degrees F. Using a small brush, lightly coat two 9-inch cake pans with softened butter or vegetable-oil cooking spray. Dust with flour and tap out any excess. Set aside. In a medium bowl, sift together flour, baking powder, salt, and baking soda and set aside. In a large bowl using a mixer set at medium speed, cream butter and sugar until light and fluffy. Add the eggs, one at a time, blending each thoroughly before adding the next. Scrape down sides and beat in vanilla extract. Reduce mixer speed to low and add the flour mixture by thirds, alternating with the lemon juice and buttermilk and ending with the dry ingredients.

2. Bake the cake: Divide the batter equally between the pans and spread evenly. Bake on the middle rack of the oven until the tops spring back when lightly touched and a tester inserted in the center of each cake layer comes out clean -- 20 to 30 minutes. Cool in the cake pans on a wire rack for 15 minutes. Using a knife, loosen the cake layers from the sides of the pans and invert the layers onto the wire rack to cool completely. Frost with lemon buttercream.

Lemon Buttercream

Serving: 3 cups

1/2 cup (about 3 large eggs) egg whites
1 cup granulated sugar
1 pound unsalted butter, cut into 1/2-inch pieces
1 tablespoon finely grated lemon zest
1 tablespoon fresh lemon juice

Make the frosting:

In a large stainless-steel bowl placed over a pot filled with 1 inch of simmering water, place the egg whites and sugar.
Use a whisk to beat the mixture until it is very hot to the touch (about 160 degrees F).
Remove from heat and, using a mixer set on high speed, immediately begin whipping the mixture until it is cool, thick, and glossy and has tripled in volume -- about 5 minutes.
Reduce mixer speed to medium and add the butter -- about a quarter cup at a time -- allowing 5 to 10 seconds in between each addition.
Add the lemon zest and lemon juice and continue to beat until smooth and fluffy.