**Ingredients:**
**For the Cake:**
– 2 1/2 cups cake flour
– 1 tablespoon baking powder
– 1/2 teaspoon salt
– 1 1/4 cups buttermilk
– 4 large egg whites
– 1 1/2 cups granulated sugar
– 2 teaspoons freshly grated lemon zest
– 1/2 cup (1 stick) unsalted butter, at room temperature
– 1/2 teaspoon pure lemon extract
**For the Buttercream:**
– 1 cup granulated sugar
– 4 large egg whites
– 1 1/2 cups (3 sticks) unsalted butter, at room temperature
– 1/4 cup freshly squeezed lemon juice (from 2 large lemons)
– 1 teaspoon vanilla extract
**For Finishing:**
– 2/3 cup seedless raspberry preserves, stirred until spreadable
– Fresh raspberries
**Directions:**
1. **Prepare the Oven and Pans:**
– Center a rack in the oven and preheat to 350°F. Butter two 8 or 9-inch round cake pans and line the bottoms with buttered parchment or wax paper. Place the pans on a baking sheet.
2. **Make the Cake:**
– Sift together the flour, baking powder, and salt.
– Whisk together the buttermilk and egg whites in a medium bowl.
– In a large bowl, combine the sugar and lemon zest, rubbing them together until the sugar is moist and fragrant.
– Add the butter to the sugar mixture and beat on medium speed for 3 minutes until light and fluffy. Mix in the lemon extract.
– Add one-third of the flour mixture, beating on medium speed. Mix in half of the milk-egg mixture, then add half of the remaining dry ingredients, mixing until incorporated. Add the rest of the milk-egg mixture and the last of the dry ingredients, beating until the batter is smooth. Beat the batter for an additional 2 minutes to ensure it is well-mixed and aerated.
– Divide the batter between the two prepared pans and smooth the tops with a rubber spatula.
– Bake for 30-35 minutes, or until a toothpick inserted into the centers comes out clean. Cool the cakes in the pans for 5 minutes, then transfer to a cooling rack to cool completely. The cakes can be stored wrapped in airtight containers at room temperature overnight or frozen for up to 2 months.
3. **Make the Buttercream:**
– In a heatproof bowl, combine the sugar and egg whites. Place the bowl over a pan of simmering water and whisk constantly until the mixture feels hot to the touch and the sugar has dissolved, about 3 minutes.
– Remove from heat and beat the mixture on medium speed until it cools, about 5 minutes. Gradually add the butter, one stick at a time, beating until smooth. Once all the butter is incorporated, beat on medium-high speed until thick and smooth, about 6-10 minutes. If the buttercream curdles or separates, continue beating until it comes together. Gradually add the lemon juice and vanilla extract, beating until absorbed.
– Press a piece of plastic wrap against the surface of the buttercream and set aside.
4. **Assemble the Cake:**
– Using a serrated knife, slice each cake layer horizontally in half.
– Place one layer, cut side up, on a cake plate. Spread a light layer of buttercream over the layer, then spread one-third of the raspberry preserves on top.
– Repeat with the next two layers, using all of the raspberry preserves and leaving some buttercream for the top and sides of the cake.
– Place the final layer, cut side down, on top of the cake. Frost the top and sides with the remaining buttercream.
– Decorate with fresh raspberries.