Preheat Your Oven and Prepare the 8-inch Round Cake Pans - Preheat your oven to 350 degrees Fahrenheit. Line your cake pans with parchment paper and then spray them with cooking spray.

Mix the Dry Ingredients - Add the all-purpose flour, granulated sugar, baking powder, and salt to a large mixing bowl. Using a large bowl with a whisk attachment, mix until fully combined.

Beat in the Butter - Cut your butter up into chunks. Slowly add the chunks of butter into the dry ingredients and beat with the mixer at low speed. Mix until no large chunks remain and the mixture is crumbly.

Add the Egg Whites - With the mixer at low speed, add the egg whites in. Mix until they become just incorporated.

Add Sour Cream, Vanilla Extract, Almond Extract, and Vegetable Oil - Add the sour cream, vanilla extract, almond extract, and vegetable oil into the cake batter. Beat on low speed until the mixture is fully combined. Scrape down the sides of the bowl using a rubber spatula and beat for a few more seconds, still at low speed.

Bake the Cakes - Among the three cake pans, divide the cake batter evenly. Bake for 33-35 minutes or until a toothpick inserted into the middle comes out clean. Allow the cakes to cool in their pans for 10 minutes atop a wire rack.

Run an offset spatula around the edge of the cakes to loosen them. Then, place them in the freezer for 45 minutes to one hour. Once cool, remove from pans and use a serrated knife to level off the tops of the cakes.

Make the Frosting - Using the electric mixer, beat the butter at medium speed for about 30 seconds, until smooth and creamy. Change the mixer to low speed and add one cup of powdered sugar at a time. Alternate with adding in splashes of the heavy whipping cream.

Once fully mixed, add the almond extract, vanilla extract, and salt. Beat on low speed until fully incorporated. Add more cream if the frosting is too thick and more powdered sugar if it is too thin.

Decorate the Cake - Stack the cake layers on top of each other, adding a layer of frosting between each cake. Add a thin layer of frosting to the sides and top of the cake using an offset spatula. Refrigerate the cake for 20 minutes and then cover with the remaining frosting.