Cake

1. Preheat oven to 350F. Spray with nonstick cooking spray or butter two 8-inch or 9-inch round cake pans. Sprinkle about a tablespoon of all purpose flour into each pan and turn to coat the pan, tapping out any excess; set aside.

2. In a liquid measuring cup or small bowl, whisk together milk, egg whites, vanilla extract and vanilla bean seeds to combine; set aside.

3. In the bowl of an electric mixer, sift together flour, sugar, baking powder, and salt. (Or pulse the mixer a few times to combine.) Add butter, a tablespoon at a time, mixing on low until mixture resembles coarse crumbs. (It’ll look a bit like the start of pastry dough.)

4. Add half the milk mixture and beat until the dough is moist and thick (a bit like cookie dough). Scrape down the sides of the bowl as needed. Add remaining milk mixture and beat until combined. (Mixture should look more like batter now.)

5. If using food coloring, divide the batter evenly between two bowls. Add enough food coloring to each to achieve the desired color, mixing well to distribute color evenly.

6. Pour divided batter into prepared cake pans, filling pans about 2/3 to ¾ of the way full. Bake, rotating pans halfway until cake springs back when touched and a toothpick inserted in the center of the cake comes out clean, about 30 to 32 minutes. Cool in cake pans on wire racks until just slightly warm. Turn cakes out of pan and allow to cool completely.

Lemon Swiss Meringue Buttercream<br /><br />

1. In a bowl set over, but not touching, a pan of simmering water, whisk together egg whites and granulated sugar until well combined. Whisking constantly, heat until sugar is completely dissolved, about 5 minutes, scraping down the sides of the bowl as needed. (To test whether the sugar is melted, rub a bit of the mixture between your fingers. It should feel smooth, not grainy, and be warm to the touch, but not hot.)

2. Pour the mixture into the bowl of an electric mixer fitted with the whisk attachment and beat on high until the bottom of the bowl is cool to the touch and the whites have formed stiff peaks.
   3. Add the butter, a tablespoon at a time, beating until each is well combined before adding the next (about 15 seconds in between). If the mixture looks very soupy after adding the butter, put it in the refrigerator to chill for about 5 to 10 minutes before continuing to beat.

3. Once the butter has been added, switch to the paddle attachment, and beat on high until light and fluffy, about 5 minutes. (The mixture will probably break and look curdled at one point—don’t worry it’s totally normal. Just keep beating away. It’ll come back together.) Once the buttercream is fluffy, add lemon extract and beat until combined.

To assemble the Cake:<br /><br />

1. Stack the bottom layer of cooled cake on a cardboard cake round (these make it 1000x easier to move the cake, and also protects your cake plate or stand from being scratched up when you’re cutting into the cake later.) Using about a cup to 1 1/2 cups of frosting for the center layer, spread the frosting out from the center of the cake until it hangs over the edges. 

2. Stack the top layer directly on top of the bottom, making sure the cake is even. Spread a very thin layer of frosting across the top and around the edges of the cake. (It doesn’t have to be perfect. This is the crumb coat that seals the cake. It’ll be covered later with the final coat of frosting, so no one will ever see it!) Refrigerate the cake until the frosting is set, about a half an hour to an hour. 

3. Once frosting is set, remove from refrigerator and frost completely with remaining buttercream. After it is completely frosted, it can be left at room temperature. (I put mine back in the fridge because my house was warm and my frosting was looking a bit melty. Just remember to take it out of the fridge about an hour before serving to let it come to room temperature, or the frosting will be hard.)