• Preheat the oven to 350 ℉. Grease and flour three 8x2 inch pans. We also added a circle of parchment to the bottom of each pan.
• In a medium bowl, whisk the cake flour, baking powder, baking soda and salt for 30 seconds. Set aside
• In another bowl, add the buttermilk, vegetable oil and vanilla. Set aside.
• In the bowl of your mixer, (and using the paddle attachment if using a stand mixer), add the butter and mix at medium speed until smooth. Gradually add the sugar and continue to mix on medium speed for 3 to 5 minutes until lightened in color and fluffy.
• Add the 6 egg whites one at a time, waiting a few seconds after each addition. (If you are using carton egg whites, just estimate. We did 6 small additions).
• With the mixer on low speed, alternately add the flour mixture and buttermilk mixture, beginning and ending with the dry ingredients (3 additions of dry ingredients and 2 of liquid). After the last addition, mix just until combined.
• Bake at 350 degrees for 25-30 minutes or until a toothpick inserted into the center comes out clean or with just a few crumbs attached.
• Let the cake layers cool in the pans 10 minutes, then turn out.
• This recipe makes 7 cups of batter. Works well for cupcakes also.

For the Sweetened Whipped Cream

• Chill the mixing bowl and beaters/ whisk attachment in the freezer for 10 minutes.
• Pour the whipping cream, powdered sugar and vanilla into the chilled mixing bowl, begin beating on low speed gradually increasing to medium high speed.
• The cream begins to thicken (approx. 1 ½ minutes) and stiff peaks for. (When you can lift the beaters or whisk attachment from the bowl and the cream stands up, it is ready.)

For the Vanilla Buttercream

• Cream the (slightly softened) butter until smooth. Blend in the vanilla.
• Add half of the powdered sugar and most of the milk. Mix at medium speed until the powdered sugar is incorporated.
• Add remaining powdered sugar and milk and mix at medium speed another 3 to 4 minutes scraping the sides of the bowl occasionally. I slow down the mixer to very slow. (#2 on the Kitchenaid) for 1 to 2 minutes. This will help eliminate air pockets in the buttercream. The texture will become very smooth.

Cake Assembly

• Place the first cake layer on cake base or pedestal.
• If using a soft filling as we did, first pipe a dam of buttercream around the edge of the cake layer (about ¼ inch from the edge). We do this by loading the frosting into a disposable piping bag and snipping the tip away.
• Add the whipped cream filling within the dam. (The dam keeps it from escaping as the layers are stacked.)
• Top with the next layer and repeat. Then, top with the third layer. Using the piping bay that you used for your dam, fill in any gaps between the cake layers. Then, apply a thin (crumb coat) of frosting. At this point, we like to chill in the freezer for 15 minutes (or longer in the refrigerator) to firm everything up.
• Finish with the final coat of frosting. Decorate however you like! We used a cake comb to comb around the sides of the cake, and then added additional frosting (tinted with pink coloring gel) to the top of the cake. We added a simple shell border around the base with a 1M large star piping tip.
• Store in an airtight container in the refrigerator (because of the perishable filling). Remove from the refrigerator 2 hours before serving for best flavor and texture, so that the cake and frosting have time to warm and soften.