Gather the ingredients you will need to make your Costco Tuxedo Cake. Preheat oven to 350°F/175°C and grease two 9-inch cake pans with parchment paper. In a medium bowl, mix together the oil, egg whites, sour cream, and vanilla extract for the vanilla cake batter until combined. In another bowl, combine the flour, sugar, salt, and baking powder for the vanilla cake. Pour wet ingredients into dry ingredients and stir until just combined. Divide batter into two prepared pans and spread evenly before placing in the oven to bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.

Make the chocolate cake by stirring together the oil, eggs, coffee, and vanilla extract in a medium bowl. In another bowl, mix together flour, cocoa powder, black cocoa powder, baking powder, sugar, milk, and salt. Pour wet ingredients into dry ingredients and stir until just combined. Divide batter into two prepared pans and spread evenly before baking in the oven for 25-30 minutes or until a toothpick inserted into the center comes out clean.

Prepare the ganache glazes by heating heavy cream in a medium saucepan until it starts to simmer, then remove from heat and add the white chocolate chips or dark chocolate chips. Stir until smooth and combined.

Assemble your masterpiece by placing one of the vanilla cakes on a cake stand or plate. Spread half of the white chocolate ganache over it, top with one of the chocolate cakes spread the remaining white chocolate ganache over it, and top with the last layer (the remaining vanilla cake). Spread dark chocolate ganache over top and serve.