Preheat the oven to 350 °F. Grease three round 9” cake pans, line the bottom with parchment paper, then grease the parchment paper.
Whisk the cake flour, salt, baking powder, and baking soda together. Set aside.
Using a handheld or stand mixer fitted with a paddle attachment, beat the butter and sugar together on high speed until smooth and creamy, about 3 min. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed.
Beat in the 3 eggs, 2 egg whites, and vanilla extract on high speed until combined, about 2 min. Scrape down the sides and up the bottom of the bowl as needed. With the mixer on low speed, add the dry ingredients just until combined.
With the mixer still running on low, pour in the buttermilk and mix just until combined. Check for clumps and whisk by hand if necessary. The batter will be slightly thick.
Pour batter evenly into cake pans. Bake for around 25-30 minutes or until a toothpick inserted into the center of the cake and it comes out clean or with just a couple of crumbs. Allow cakes to cool completely in the pans set on a wire rack. The cakes must be completely cool before frosting and assembling.
Vanilla Buttercream Frosting Instructions
In a stand mixer fitted with a paddle attachment, beat the butter on medium speed until creamy, about 2 min. Add powdered sugar, milk, vanilla extract, and salt with the mixer running on low. Increase to high speed and beat for 2 min.
Add more confectioners’ sugar if frosting is too thin, more milk if frosting is too thick, or an extra pinch of salt if frosting is too sweet.
Assembly
Using a large serrated knife, slice a thin layer off the tops of the cakes to create a flat surface.
Place 1 cake layer on your cake stand, cake turntable, or serving plate. Evenly cover the top with about 1 and ½ cups of frosting. Top with 2nd cake layer and evenly cover the top with about 1 and ½ cups of frosting.
Top with the third cake layer. Spread the remaining frosting all over the top and sides.
Refrigerate cake for at least 1 hour before slicing. Enjoy
Notes
Don't overmix the batter once you add the flour - this develops gluten and makes your cake tough.
Lightly tap the cake pans once filled with the batter to remove large air bubbles. Some air bubbles are normal, however.
Check for doneness early - all ovens are different! A toothpick inserted in the center should come out clean or with a few moist crumbs.
Let the cakes cool completely before frosting - otherwise, your frosting will melt!
Room temperature ingredients are a must! Cold eggs or buttermilk can cause the batter to curdle. Room temperature butter means that when pressed with your finger it leaves a dent, not melted or runny.
If using curd or jam, be careful you don't add too much filling between layers. The weight of the top cake will press the filling down even more and cause it to seep over the edges into the frosting. Instead, use less filling than you think you need and spread it out to within an inch of the edges of the layer but no further.
Level out the layers before stacking them otherwise your cake will have a domed effect and can crack down the center. It will also make it difficult to cut.
This frosting recipe makes enough for a 9x13 or 2-9-inch round cake pans. Increase the recipe by at least 25% if making a three-layered cake as pictured.
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.