Preheat the oven to 350 degrees Fahrenheit (180 degrees Celsius). Line 3 metal 6-inch round cake pans with parchment paper and set aside.

Add cake flour, granulated sugar, baking powder, baking soda, and salt to the bowl of a hand mixer or stand mixer fitted with the paddle attachment. Mix on low until combined.

Beat in the butter on medium speed for 3-5 minutes until the dry ingredients are coated with butter. The mixture should look like wet sand.

In a separate bowl, whisk sour cream and milk together. Then whisk in the oil, whole eggs, egg whites, and vanilla.

Pour the wet ingredients into the dry ingredients and butter. Beat on low speed until combined with a few lumps. Don't overmix.

Evenly distribute the cake batter between the prepared pans using a cookie scoop. Bake for 30-40 minutes or until a toothpick inserted in the center comes out clean with a few moist crumbs.

Take the cakes out of the oven. Let cool in the pans for 10 minutes, then turn onto a wire rack to cool completely.

Add white chocolate to a microwave-safe bowl. Microwave in 20 second intervals, stirring after each until smooth. Set aside.

Cream softened cream cheese and butter in the bowl of a stand mixer with the paddle attachment or electric hand mixer on medium-high speed until smooth. Then beat in the powdered sugar on low 1 cup at a time.

Mix in the melted chocolate, vanilla, and salt on low. Increase the speed to medium-high until light and fluffy.

Place the first cake layer on a cake stand. Evenly spread ½ cup frosting on it. Repeat with the second layer.

Place the last cake layer on top with the flat side up. Apply a thin coat of frosting on top and around the sides of the cake. Chill for 20 minutes or until dry to the touch.

Spread the rest of the frosting on top of the cake and work it down the sides with an offset spatula. Gently smooth out the sides with the icing scraper.

Once the cake is frosted, add white chocolate ganache, festive sprinkles, or pipe buttercream swirls on top. Slice and enjoy!