For the cake: Preheat the oven to 350 degrees F. Grease eight 9-inch cake pans with cooking spray.
Add the milks, butter, vanilla, salt, eggs and cake mix to a stand mixer fitted with a paddle attachment and mix on low speed until fully combined. Evenly divide the cake batter between the cake pans, about 1/2 cup per pan. Bake until the edges are nicely browned and pulling away from the sides of the pan, 6 to 8 minutes.
Let the cakes cool on damp kitchen towels.
For the frosting: Meanwhile, heat the sugar, butter, cocoa and evaporated milk in a medium pot over medium heat, stirring constantly, until thoroughly combined. Let cool about 5 minutes prior to frosting.
Once the cakes have cooled, frost and stack each cake layer. Allow to rest about 1 hour before slicing.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. The Food Network Kitchens chefs have not tested this recipe and therefore, we cannot make representation as to the results.