Lemon Vanilla Layer Cake with Blueberry Curd
Makes one four-layer 8-inch cake
For the lemon cake:
2 and 1/3 cups cake flour + more for the pans (you can make your own cake flour too)
2 and 3/4 teaspoons baking powder
1/4 teaspoons salt
1 and 3/4 cups sugar
2 Tablespoons lemon zest
3/4 cup unsalted butter, room temperature
1 cup whole milk, room temperature
5 large egg whites, room temperature
1/4 teaspoon cream of tartar
1 recipe blueberry curd
For the vanilla bean frosting:
1 cup (two sticks) unsalted butter, room temperature
3 and 1/2 cups confectioners' sugar
1-3 Tablespoons milk
1 vanilla bean
1 teaspoon vanilla extract
Make the cake! Place oven rack in the middle of the oven. Preheat to 350 degrees F. Generously grease and flour two 8 x 2-inch round cake pans (I like to grease the bottom, then line it with a circle of parchment paper and grease/flour again. Helps the cake to pop right out once it's done). Sift together the cake flour, baking powder, and salt in a medium bowl. Pulse 1/4 cup of the sugar with lemon zest in a food processor until well combined.
In a large bowl, beat together the butter and lemon sugar with an electric mixer until light and fluffy, about 2 minutes. Add the remaining 1 and 1/2 cups of sugar and beat for another 90 seconds. Beat in a quarter of the milk until just blended. Keeping the mixer on low speed, alternate adding the flour mixture and milk in three batches, making sure to scrape the sides of the bowl. Beat until just blended.
In another large bowl, beat the egg whites with electric mixer on medium speed until just foamy. Make sure to use clean beaters. Add the cream of tartar, increase the speed to medium high, and beat just until stiff peaks are formed. You can test this by lifting the beaters out of the mixture and seeing if the peaks hold. Add a quarter of the whites to the batter and gently fold them in using a whisk or rubber spatula. Slowly fold in the rest of the whites, being careful not to deflate the mixture.
Split up the batter evenly into the two prepared pans, smoothing the tops with a spatula. Bake for 35-40 minutes, or until a toothpick inserted into the centers comes out clean. Remove from oven and let cakes cool in the pans on a rack for 10 minutes. Run a knife along the edges of the pans and carefully invert each cake onto the rack. Flip them right side up and let them cool completely.
Make the frosting! In a large bowl, beat room temperature butter on medium-high speed for about 1 minute. Slowly add 2 cups confectioners sugar and beat together to combine. Slowly add milk one tablespoon at a time, adding more sugar if the frosting becomes too thin and adding more milk if it is too dry. Add vanilla extract. Scrape out the insides of one vanilla bean and beat into the mixture.
Put it all together! Once cooled, wrap each layer individually in plastic wrap and stick in the freezer for about an hour. This will keep the layers from breaking. Afterwards, take a long serrated knife and cut each cake layer in half horizontally. Keep one hand pressed on top of the cake while slicing. You should now have four equal layers.
Spread blueberry curd between each layer and stack on top of one another. Use an offset spatula to crumb-coat the cake, then cover with plastic wrap and freeze for 30 minutes. Remove from freezer and frost the cake to your heart's content.